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Friday was a big day of adventure and learning for me.
I had worked some long hours Monday through Thursday, and so needed to go in to work for only 3 hours. So, I arranged to be at MTI Racing very early in the morning with an already cooled down SSR, so that when they opened for the day, they could install my brand new Dynatech Supermaxx headers – the deluxe version of the kit – with the hi-flow cats (specify pn 115-735-300S. It is the “S” that adds the costly cats). Things got much more interesting than that though, as it turned out.
I had been invited there by Paul Smith. Paul used to be the President of Kroger Atlanta, responsible for 200 grocery stores in multiple states, but in his retirement is partnering with, and advising, Reese Cox, the owner of MTI Racing. MTI is an exclusively C5 and C6 Corvette shop located in the nowrthwestern suburbs of Atlanta.
Paul and I had been trying for weeks to get together, but our schedules kept getting ruffled. As we talked over those many weeks, he got more and more interested in what I was doing in analyzing and projecting SSR performance improvements, via gearing, external-to-engine modifications, and computer simulation.
In fact, I did some analysis on his own car, a 98 C5, and testbed for many ofMTI’s offerings, whose performance can only be described as “inspiring”. Paul’s car has a very interesting powertrain that includes the GM automatic used in the C5, complete with its insane ratio drop between 1st and 2nd. Paul’s dyno curve show a horsepower peak of “only” 405 hp net at the rear wheels (with an automatic!!), but that peak starts at about 6250rpm and runs without valve float to 7000 rpm, where Reese shuts down the festivities in the interests of durability. Consequently, I told him the best strategy with this car was to shift at as high an rpm as he felt comfortable with, as the computer says that that very high and flat peak makes this the best strategy with that set of tranny ratios. With the effects of the 3500 rpm stall converter, the net torque peak on the dyno, after all losses, is about 510 ft lb, and occurs at a VERY low rpm of about 3250. You can begin to imagine how torquey this car must feel on the track and the road. Here’s the punchline: Paul’s car runs the quarter in 11.07 seconds at 123 mph, which is nice enough, but his 60 foot time is a breathtaking 1.53 seconds! My software says he is doing better than 40 mph at that 1.53 second mark, and that he clears 60 mph in well under 3 seconds. He clears 100 mph in about 7 seconds. (Remember Paul’s “mild” horsepower and torque numbers, and resulting performance, later when I describe “Chuck’s” car below!!)
When I asked Paul how much I should expect to spend for header installation at another good shop (remember that MTI does exclusively Corvettes), he asked me to stand by for a day while he talked to Reese. He ended up calling me back and saying that Reese would be delighted to do the install this Friday if I could get the headers delivered in time. He told me that he and Reese had an interest in exploring the potential of adding SSRs to their repertoire, and in utilizing my computer simulation capabilities for driveline design. So, here I was, early Friday morning, at their shop, waiting for someone to show up.
At around 8:45am, 15 minutes before opening time, a black C5 Corvette that looked very “stock” but had a much louder and throatier than normal exhaust pulled into the lot, and a man a bit older than me stepped out and introduced himself as Chuck Wolf. It turned out that Chuck was not an MTI employee, but rather a client, and also a supplier. He explained that he had just picked up his car yesterday from MTI, so it only had under 30 miles on it since “the work” was done on it. He asked if I would like to go for a ride in it. (Would I like to see J Lo naked? Sure!!)
As he drove down the road, he explained why the car has a stick shift lever but he was not shifting gears. His car had started as a 6-speed, but he wanted an automatic installed along with “the work”. Reese, egged on by Paul, managed to pull that off. Among other things, it required a COMPLETE new vehicle wiring harness, as the 6-speed harness is entirely different than the automatic one. I was still digesting that when Chuck very quietly mentioned that this car we were now in had produced on the dyno, after all driveline losses, with a “mild” cam, and after the automatic, a NET of 590 ft lb of torque. The car has a 4.10 axle. I was still digesting the importance of all that information, and recalling Paul’s torque and performance figures (above!), when Chuck did a u-turn on the highway and nailed it in 1st.
Let’s just say that this was easily the quickest and most exciting ride I have been on, and that includes driving some of the World’s quickest stock motorcycles. The car fishtailed ALL the way through 1st and into 2nd and pinned you back as effectively as a really quick bike. The tires sounded like death HAD to be imminent. And that folks, was with TWO of us in the car, and while Chuck is average in build, I am not at 235 lb! I’m absolutely certain that everyone else near us on that highway, including the cargo truck we fishtailed past, was wondering when the air force had started sending stealth fighters down GA 120 with two big toothy grins painted onto the cockpit windows. This is the most urgent sounding car I’ve certainly ever been in. Remember Paul’s performance specs above? This car is MUCH quicker than THOSE.
At the next light, Chuck asked if I’d like to drive it (Would I like to actually TOUCH J Lo when she is naked???). I was outside and over to the driver’s side of the car before Chuck even had his seatbelt unfastened.
I don’t like to take ANY chances when driving my own car, and fewer yet when driving someone else’s (the “You did WHAT to my baby??” scenes are ugly). So I never got it beyond about half throttle, but let me tell you, I definitely was very impressed. This is in the league of seriously superfluous power being produced by seriously twisted and demented people who just don’t know when enough is enough (my kind of people!!!). And the stealth factor is beautiful. You’d never guess that the mature gentleman in the conservative looking car next to you is about to unleash Hell’s fury.
After that very effective introduction to MTI’s capabilities, I returned to the shop to meet Paul and Reese, and get a tour of the shop. They have recently doubled both their staffing and the floor space they lease, have an in-ground Dynojet dyno, and taunt visitors with 427 cubic inch SMALL BLOCK chevy engine blocks on display in the showroom. It turns out that Chuck is the supplier who bores out those blocks for them, and that the engine in his car (which made such an impression on me above) is one of these 427s made out of an LS1. (Yes, gentlemen, our LM4 in those 03 and 04 SSRs is indeed an LSI block). To the casual underhood observer, it’s NOT a “big” motor under that hood. Don’t race these guys for money, folks.
By the way, the deceptively mild-mannered and quiet Chuck has extreme tastes that run well beyond really quick cars. Paul told me that he will take me over to Chuck’s shop some time and show me the INDOOR soccer field that Chuck has in there, complete with a surface much better than lowly “Astroturf”. I think I have finally found a group of people whose tastes run as extreme as mine. I may have stumbled into Heaven . . .
Reese had told Paul and I that his people would be ready to start work on the headers for my SSR first thing (that’s why I came 1.5 hours early to give the vehicle time to cool down completely before they opened). But, Reese being who he is (a race car driver and gifted vehicle magician, easily absorbed and fixated by new challenges), that’s not what happened. Reese wanted before and after dyno results for my SSR, and so put it on the Dynojet. THAT turned out to be the start of a very long R&D session because Reese simply got very interested in my SSR.
You can really tell when you have a Pro around your vehicle. Reese found that the folks who had done my rear axle swap had overtorqued a bolt on the axle inspection cover, and snapped the head off, without telling me (Paul says Rees’s guys will drill it out and replace it). He also pronounced one of the O2 sensors as marginal.
I had asked him to run the SSR on the dyno to as high an rpm as he felt was safe, as my earlier dyno run at Walden had stopped at 5600 rpm, because the shift points had not been raised as I had asked them to be during the HP Tuner session. Reese overrode the onboard computer settings and spun the engine to 6500 rpm, where he stopped simply because the shape of the curve at that point was so stably predictable that any higher was unnecessary. Remember, this is a stock factory LM4, not a built engine with special “high rpm capable” components. Paul told me that Reese has NEVER had an LS1 lower end fail in any way, and that the valvetrain on the modern Chevy engines is much more capable than you would think. Our LS1 based LM4 5.3 L engines have 6 bolt mains, cast cranks but undercut and rolled fillets that are internally balanced, and a low friction, roller (stamped) rocker valvetrain.
The peak power numbers I got from Reese and from Walden were close to identical, so both dynos are consistent with each other. But, Reese’s dyno results for my SSR were first of all much cleaner and much easier to read than the ones I got at Walden. The power curve generated was VERY consistent from run to run – so much so that they lines just overwrote each other when displayed simultaneously. Both Reese and Walden re-stated something that I had heard amny time before too: When you regear a vehicle, the Dynojet shows a substantially lower power curve than before the regearing. This is a function of the way a Dynojet inertia type dyno works. You can easily verify this by doing a multi-gear run on a dyno. You will see that the power curves get lower as you cycle from 1st gear through 2nd, 3rd, and 4th. I haven’t had time yet to do the analysis to figure out why this is so.
I am SO glad that I asked Reese to run the engine to those higher rpms, because the engine’s performance there is nothing short of miraculous considering that we are talking about an engine normally used in everyday Tahoes, Silverados, and Trailblazers – NOT an engine built with “performance” use in mind.
The engine peaked at about 254 to 256 hp (that’s the magnitude of the deviation between runs, guys!). The SHAPES of both the torque curve and the power curve were very interesting and very “right”.
I have consistently high flat torque from 3800 rpm where the dyno data starts all through 4900 rpm. I`m talking that entire range deviating no more than 10 ft lbs from a wide peak of 270 ft lb at the rear wheels. From 4900, the torque falls almost linearly to 170 ft lb at 6500 rpm.
The power curve peaks at 254 to 256 hp at around 5200 to 5400 rpm, but still has 210 hp available at 6500 rpm, versus the much lower power available at rpm below 3500 (180hp or less). THIS is why my SSR is 0.3 second quicker from 0 to 60 mph when you shift at 6000 instead of 5600 rpm! If I could bring myself to shift at 6500 (I cannot! I just don’t feel THAT confident about a stock LM4 spinning that fast in daily use, at least until Reese can reassure me “it’s ok”), I would see another tenth or a bit more reduction in that time. All this is for exactly the same reason that Paul’s C5 does better when wrung out to close to 7000: That darn automatic simply has a 1st gear ratio that is too high for PERFORMANCE use, because it drops the engine right off its power curve when you make the shift to 2nd.
The above MTI horsepower curve is reasonably consistent with the performance I actually got on my last instrumented road testing: 0 to 60 mph time of 6.5 seconds and quarter mile time of 15.07 at 92 mph, with me (235 lb) and 15 gallons of fuel aboard. Both times would be quicker of course with a 160 lb “standard” driver and 2 gallons of fuel aboard. I had to extrapolate the power curve below 3800 rpm of course, using the shape of the power curve deduced by the G-Tech, so I am NOT going to claim precision matching here, but we have usable consistency.
In addition, my power and torque curve are reasonably consistent with the ones that 04Z16 was gieven by HIS shop when he got the same comparison done before and after his Supermaxx headers installation. His peak “before” power number happened to be 249.4, but that might be just because my SSR came into its “before”session having gone through an HP Tuner dyno tuning session at Walden.
I think Reese really knows what he is doing, guys, both mechanically and on the dyno.
His guys got part of the header install done Friday afternoon before they left for the day, but it will need to be finished Monday. Paul apologized for the delay, but explained it was caused by Reese’s fascination with the SSR. Because I have no other transportation here at the moment, Paul asked my permission to extend to Monday BEFORE they started the headers, and said MTI would pick up the cost of my rental car for the duration. That made a favorable impression on me. It’s nice to know that when there are deviations from plan, the shop is not going to simply say “oops” and let YOU deal with it. Paul having been in the highly service-oriented grocery business, knows the importance of good customer service, and the unpurchaseable advertising value of GREAT customer service.
Paul told me today that he and Reese would like to use my SSR as a test bed for ideas that will ultimately go into an array of “packages” that MTI will offer SSR owners. Those packages will possibly publish specific performance improvement specs, so that you can choose the package that gives you the performance specs you want. Naturally, you can build on most of the packages to go to the next level of performance later by buying a subsequent package. I think they need to run some experiments on my SSR to see what can be done, what is effective, and what cost effective “good bang for the buck” packages can be structured.
So, I cannot yet report the before and after power results for the Dynatech Supermaxx headers to you as I had hoped to do this weekend. On the other hand, I hope you agree that what I brought you instead in this thread make the delay worthwhile! We may have found a pro shop that is interested in working with us to get the LM4 versio of the SSR to its potential. Naturally, since MTI is already a Corvette shop, the 05 SSR should be easy for them to adapt to also.
Stay tuned. Potentially exciting times ahead.
Jim G
I had worked some long hours Monday through Thursday, and so needed to go in to work for only 3 hours. So, I arranged to be at MTI Racing very early in the morning with an already cooled down SSR, so that when they opened for the day, they could install my brand new Dynatech Supermaxx headers – the deluxe version of the kit – with the hi-flow cats (specify pn 115-735-300S. It is the “S” that adds the costly cats). Things got much more interesting than that though, as it turned out.
I had been invited there by Paul Smith. Paul used to be the President of Kroger Atlanta, responsible for 200 grocery stores in multiple states, but in his retirement is partnering with, and advising, Reese Cox, the owner of MTI Racing. MTI is an exclusively C5 and C6 Corvette shop located in the nowrthwestern suburbs of Atlanta.
Paul and I had been trying for weeks to get together, but our schedules kept getting ruffled. As we talked over those many weeks, he got more and more interested in what I was doing in analyzing and projecting SSR performance improvements, via gearing, external-to-engine modifications, and computer simulation.
In fact, I did some analysis on his own car, a 98 C5, and testbed for many ofMTI’s offerings, whose performance can only be described as “inspiring”. Paul’s car has a very interesting powertrain that includes the GM automatic used in the C5, complete with its insane ratio drop between 1st and 2nd. Paul’s dyno curve show a horsepower peak of “only” 405 hp net at the rear wheels (with an automatic!!), but that peak starts at about 6250rpm and runs without valve float to 7000 rpm, where Reese shuts down the festivities in the interests of durability. Consequently, I told him the best strategy with this car was to shift at as high an rpm as he felt comfortable with, as the computer says that that very high and flat peak makes this the best strategy with that set of tranny ratios. With the effects of the 3500 rpm stall converter, the net torque peak on the dyno, after all losses, is about 510 ft lb, and occurs at a VERY low rpm of about 3250. You can begin to imagine how torquey this car must feel on the track and the road. Here’s the punchline: Paul’s car runs the quarter in 11.07 seconds at 123 mph, which is nice enough, but his 60 foot time is a breathtaking 1.53 seconds! My software says he is doing better than 40 mph at that 1.53 second mark, and that he clears 60 mph in well under 3 seconds. He clears 100 mph in about 7 seconds. (Remember Paul’s “mild” horsepower and torque numbers, and resulting performance, later when I describe “Chuck’s” car below!!)
When I asked Paul how much I should expect to spend for header installation at another good shop (remember that MTI does exclusively Corvettes), he asked me to stand by for a day while he talked to Reese. He ended up calling me back and saying that Reese would be delighted to do the install this Friday if I could get the headers delivered in time. He told me that he and Reese had an interest in exploring the potential of adding SSRs to their repertoire, and in utilizing my computer simulation capabilities for driveline design. So, here I was, early Friday morning, at their shop, waiting for someone to show up.
At around 8:45am, 15 minutes before opening time, a black C5 Corvette that looked very “stock” but had a much louder and throatier than normal exhaust pulled into the lot, and a man a bit older than me stepped out and introduced himself as Chuck Wolf. It turned out that Chuck was not an MTI employee, but rather a client, and also a supplier. He explained that he had just picked up his car yesterday from MTI, so it only had under 30 miles on it since “the work” was done on it. He asked if I would like to go for a ride in it. (Would I like to see J Lo naked? Sure!!)
As he drove down the road, he explained why the car has a stick shift lever but he was not shifting gears. His car had started as a 6-speed, but he wanted an automatic installed along with “the work”. Reese, egged on by Paul, managed to pull that off. Among other things, it required a COMPLETE new vehicle wiring harness, as the 6-speed harness is entirely different than the automatic one. I was still digesting that when Chuck very quietly mentioned that this car we were now in had produced on the dyno, after all driveline losses, with a “mild” cam, and after the automatic, a NET of 590 ft lb of torque. The car has a 4.10 axle. I was still digesting the importance of all that information, and recalling Paul’s torque and performance figures (above!), when Chuck did a u-turn on the highway and nailed it in 1st.
Let’s just say that this was easily the quickest and most exciting ride I have been on, and that includes driving some of the World’s quickest stock motorcycles. The car fishtailed ALL the way through 1st and into 2nd and pinned you back as effectively as a really quick bike. The tires sounded like death HAD to be imminent. And that folks, was with TWO of us in the car, and while Chuck is average in build, I am not at 235 lb! I’m absolutely certain that everyone else near us on that highway, including the cargo truck we fishtailed past, was wondering when the air force had started sending stealth fighters down GA 120 with two big toothy grins painted onto the cockpit windows. This is the most urgent sounding car I’ve certainly ever been in. Remember Paul’s performance specs above? This car is MUCH quicker than THOSE.
At the next light, Chuck asked if I’d like to drive it (Would I like to actually TOUCH J Lo when she is naked???). I was outside and over to the driver’s side of the car before Chuck even had his seatbelt unfastened.
I don’t like to take ANY chances when driving my own car, and fewer yet when driving someone else’s (the “You did WHAT to my baby??” scenes are ugly). So I never got it beyond about half throttle, but let me tell you, I definitely was very impressed. This is in the league of seriously superfluous power being produced by seriously twisted and demented people who just don’t know when enough is enough (my kind of people!!!). And the stealth factor is beautiful. You’d never guess that the mature gentleman in the conservative looking car next to you is about to unleash Hell’s fury.
After that very effective introduction to MTI’s capabilities, I returned to the shop to meet Paul and Reese, and get a tour of the shop. They have recently doubled both their staffing and the floor space they lease, have an in-ground Dynojet dyno, and taunt visitors with 427 cubic inch SMALL BLOCK chevy engine blocks on display in the showroom. It turns out that Chuck is the supplier who bores out those blocks for them, and that the engine in his car (which made such an impression on me above) is one of these 427s made out of an LS1. (Yes, gentlemen, our LM4 in those 03 and 04 SSRs is indeed an LSI block). To the casual underhood observer, it’s NOT a “big” motor under that hood. Don’t race these guys for money, folks.
By the way, the deceptively mild-mannered and quiet Chuck has extreme tastes that run well beyond really quick cars. Paul told me that he will take me over to Chuck’s shop some time and show me the INDOOR soccer field that Chuck has in there, complete with a surface much better than lowly “Astroturf”. I think I have finally found a group of people whose tastes run as extreme as mine. I may have stumbled into Heaven . . .
Reese had told Paul and I that his people would be ready to start work on the headers for my SSR first thing (that’s why I came 1.5 hours early to give the vehicle time to cool down completely before they opened). But, Reese being who he is (a race car driver and gifted vehicle magician, easily absorbed and fixated by new challenges), that’s not what happened. Reese wanted before and after dyno results for my SSR, and so put it on the Dynojet. THAT turned out to be the start of a very long R&D session because Reese simply got very interested in my SSR.
You can really tell when you have a Pro around your vehicle. Reese found that the folks who had done my rear axle swap had overtorqued a bolt on the axle inspection cover, and snapped the head off, without telling me (Paul says Rees’s guys will drill it out and replace it). He also pronounced one of the O2 sensors as marginal.
I had asked him to run the SSR on the dyno to as high an rpm as he felt was safe, as my earlier dyno run at Walden had stopped at 5600 rpm, because the shift points had not been raised as I had asked them to be during the HP Tuner session. Reese overrode the onboard computer settings and spun the engine to 6500 rpm, where he stopped simply because the shape of the curve at that point was so stably predictable that any higher was unnecessary. Remember, this is a stock factory LM4, not a built engine with special “high rpm capable” components. Paul told me that Reese has NEVER had an LS1 lower end fail in any way, and that the valvetrain on the modern Chevy engines is much more capable than you would think. Our LS1 based LM4 5.3 L engines have 6 bolt mains, cast cranks but undercut and rolled fillets that are internally balanced, and a low friction, roller (stamped) rocker valvetrain.
The peak power numbers I got from Reese and from Walden were close to identical, so both dynos are consistent with each other. But, Reese’s dyno results for my SSR were first of all much cleaner and much easier to read than the ones I got at Walden. The power curve generated was VERY consistent from run to run – so much so that they lines just overwrote each other when displayed simultaneously. Both Reese and Walden re-stated something that I had heard amny time before too: When you regear a vehicle, the Dynojet shows a substantially lower power curve than before the regearing. This is a function of the way a Dynojet inertia type dyno works. You can easily verify this by doing a multi-gear run on a dyno. You will see that the power curves get lower as you cycle from 1st gear through 2nd, 3rd, and 4th. I haven’t had time yet to do the analysis to figure out why this is so.
I am SO glad that I asked Reese to run the engine to those higher rpms, because the engine’s performance there is nothing short of miraculous considering that we are talking about an engine normally used in everyday Tahoes, Silverados, and Trailblazers – NOT an engine built with “performance” use in mind.
The engine peaked at about 254 to 256 hp (that’s the magnitude of the deviation between runs, guys!). The SHAPES of both the torque curve and the power curve were very interesting and very “right”.
I have consistently high flat torque from 3800 rpm where the dyno data starts all through 4900 rpm. I`m talking that entire range deviating no more than 10 ft lbs from a wide peak of 270 ft lb at the rear wheels. From 4900, the torque falls almost linearly to 170 ft lb at 6500 rpm.
The power curve peaks at 254 to 256 hp at around 5200 to 5400 rpm, but still has 210 hp available at 6500 rpm, versus the much lower power available at rpm below 3500 (180hp or less). THIS is why my SSR is 0.3 second quicker from 0 to 60 mph when you shift at 6000 instead of 5600 rpm! If I could bring myself to shift at 6500 (I cannot! I just don’t feel THAT confident about a stock LM4 spinning that fast in daily use, at least until Reese can reassure me “it’s ok”), I would see another tenth or a bit more reduction in that time. All this is for exactly the same reason that Paul’s C5 does better when wrung out to close to 7000: That darn automatic simply has a 1st gear ratio that is too high for PERFORMANCE use, because it drops the engine right off its power curve when you make the shift to 2nd.
The above MTI horsepower curve is reasonably consistent with the performance I actually got on my last instrumented road testing: 0 to 60 mph time of 6.5 seconds and quarter mile time of 15.07 at 92 mph, with me (235 lb) and 15 gallons of fuel aboard. Both times would be quicker of course with a 160 lb “standard” driver and 2 gallons of fuel aboard. I had to extrapolate the power curve below 3800 rpm of course, using the shape of the power curve deduced by the G-Tech, so I am NOT going to claim precision matching here, but we have usable consistency.
In addition, my power and torque curve are reasonably consistent with the ones that 04Z16 was gieven by HIS shop when he got the same comparison done before and after his Supermaxx headers installation. His peak “before” power number happened to be 249.4, but that might be just because my SSR came into its “before”session having gone through an HP Tuner dyno tuning session at Walden.
I think Reese really knows what he is doing, guys, both mechanically and on the dyno.
His guys got part of the header install done Friday afternoon before they left for the day, but it will need to be finished Monday. Paul apologized for the delay, but explained it was caused by Reese’s fascination with the SSR. Because I have no other transportation here at the moment, Paul asked my permission to extend to Monday BEFORE they started the headers, and said MTI would pick up the cost of my rental car for the duration. That made a favorable impression on me. It’s nice to know that when there are deviations from plan, the shop is not going to simply say “oops” and let YOU deal with it. Paul having been in the highly service-oriented grocery business, knows the importance of good customer service, and the unpurchaseable advertising value of GREAT customer service.
Paul told me today that he and Reese would like to use my SSR as a test bed for ideas that will ultimately go into an array of “packages” that MTI will offer SSR owners. Those packages will possibly publish specific performance improvement specs, so that you can choose the package that gives you the performance specs you want. Naturally, you can build on most of the packages to go to the next level of performance later by buying a subsequent package. I think they need to run some experiments on my SSR to see what can be done, what is effective, and what cost effective “good bang for the buck” packages can be structured.
So, I cannot yet report the before and after power results for the Dynatech Supermaxx headers to you as I had hoped to do this weekend. On the other hand, I hope you agree that what I brought you instead in this thread make the delay worthwhile! We may have found a pro shop that is interested in working with us to get the LM4 versio of the SSR to its potential. Naturally, since MTI is already a Corvette shop, the 05 SSR should be easy for them to adapt to also.
Stay tuned. Potentially exciting times ahead.
Jim G
