Real Turbo SHO

[Toolman]

Ooh la la Murph, very zexy!

 

[SuperHO]

I didn't think 3rd gear was drag limited, unless something is really wrong with the car.

my 3rd gear stops at 93mph......









....but for that, I can thank my clutch.......

 

[SeiGGy]

ok guys...well all the NC guys got to take a look at the Turbo SHO today, and wow it was nice hearing that wastegate open...Paul has done a truely unique setup with this turbo, and a lot of us are talking with him on perfecting his designs...the guy really knows his stuff (after all he does work around turbo-diesels all the time...) and we were beyond excited to hear/see this monster in action...so once again...major kudos to NCTaurusSHO for pushing the envelope...and all on a stock motor too...anyhow...video will be posted soon as google verifies it for me...he made posi-stripes in the lot all the way thru second gear!! and didnt sheer the diff!! kick ***

 

[nc89sho]

yup.. i like it and i want one.. from me.

 

[SeanMc]

my 3rd gear stops at 93mph......









....but for that, I can thank my clutch.......

My 2nd gear tops out at 92mph . All on a stock ATX tranny

 

[SuperHO]

betcha I get there quicker, though.....

 

[shogansta]

When i saw those pics all i could say and think was MMMMMM TUrBo!!! Nice job im planing on supercharging my 91 sho plus but i do wonder which one give out more ponies a supercharger or a turbo CAN SOMEONE ANSWER THAT PleASe thanks

 

[MYSHO1]

depends on set up, psi of boost ect....

Turbo on my gen 2 starts in a few weeks... JYI chris (SHO-Ripper) got his turbo running right

 

[ManySHOs]

...anyhow...video will be posted soon as google verifies it for me...he made posi-stripes in the lot all the way thru second gear!! and didnt sheer the diff!! kick ***

Ahh..so where's the video?

Ian

 

[jedhead]

When i saw those pics all i could say and think was MMMMMM TUrBo!!! Nice job im planing on supercharging my 91 sho plus but i do wonder which one give out more ponies a supercharger or a turbo CAN SOMEONE ANSWER THAT PleASe thanks

Many of the Vortech setups will give you more horsepower, but if you looked at Toolman's dynosheet he has a lot more midrpm torque. Keep in mind that it is torque that accelerates the car. All the mods I do to my car is to get as much torque over a wide rpm range, which is the reason I went with a Stage 1 Cam over a stage 2. I would have got more hp with stage 2 but I will have more tq over a larger rpm range. When looking at dyno curves I look at the area under the torque curve.
The main reason our SHO are fast for the small engine we have is the wide flat torque curve we enjoy.

Bob

 

[SHOMurph]

Many of the Vortech setups will give you more horsepower, but if you looked at Toolman's dynosheet he has a lot more midrpm torque. Keep in mind that it is torque that accelerates the car. All the mods I do to my car is to get as much torque over a wide rpm range, which is the reason I went with a Stage 1 Cam over a stage 2. I would have got more hp with stage 2 but I will have more tq over a larger rpm range. When looking at dyno curves I look at the area under the torque curve.
The main reason our SHO are fast for the small engine we have is the wide flat torque curve we enjoy.

Bob

yes but superchargers are faster.

 

[Toolman]

If I recall Murph, you have never beat a turbo SHO eh? HAHAHA!

 

[texantony]

If I recall Murph, you have never beat a turbo SHO eh? HAHAHA!

Well if I recall Tim, you have never beaten This supercharged SHO Haha . Not once, but twice...............over and over and over .

 

[SHOMurph]

If I recall Murph, you have never beat a turbo SHO eh? HAHAHA!

Soon soon I'll be your huckleberry!

 

[Lance Cheney]

Many of the Vortech setups will give you more horsepower, but if you looked at Toolman's dynosheet he has a lot more midrpm torque. Keep in mind that it is torque that accelerates the car. All the mods I do to my car is to get as much torque over a wide rpm range, which is the reason I went with a Stage 1 Cam over a stage 2. I would have got more hp with stage 2 but I will have more tq over a larger rpm range. When looking at dyno curves I look at the area under the torque curve.
The main reason our SHO are fast for the small engine we have is the wide flat torque curve we enjoy.

This seems to be a popular misconecption ... It's the torque at the wheels (when multiplied by the transmission) that matters -- this is NOT what you are looking at on that dyno curve; though you can derive it for each gear. Think about it this way... If I have a stage II cammed motor making 170 'wheel' ft-lbs at 7500 RPM with one set of cams, and you're running 2nd gear (~71 mph), vs. a stage I setup with a 'nice wide torque band', peaking at 210 'wheel' ft-lbs, all of which is available at the equivalent RPM for 3rd gear -- 4950 RPM, which one is going to accelerate faster at that moment?

The stage II motor is making 243whp. The stage I motor is making only 198whp. The real torque at the wheels for the stage II motor is that measured 170 ft-lbs times the transmission multiplier, which is 2.09 * 3.74 = 1330 ft-lbs. The real torque for the stage I motor is 210 * 1.38 * 3.74 = 1083 ft-lbs. Notice that 243/198 = 1330/1083... (granted, different gears have different losses so this IS an approximately, but you can see the idea).

Accelerating is ALWAYS a function of the net horsepower available at any given moment. This can be gearing constrained; launching your car is a good example -- you always start in 1st, so you will lose time if you have less torque at the low end of the RPM range, which may or may not be made up by more torque at the top end of the RPM range, depending on how long you are at each given RPM. It the hypothetical stage II motor above had only 190 ft-lbs of torque, peak, and even poorer midrange performance (say, 175ft-lbs at 5500 RPM -- you get stuck at that RPM during shifts from 2nd to 3rd, even shifting out at 8000 RPM) then the stage I motor would walk all over it in an acceleration contest -- NOT because the torque curve is peaky (it's not), but because the horsepower curve is peaky.

If you know the loss factors you can build charts of MPH vs. real wheel torque available for each valid gear. The right gear would be the one that gives you the most effect real wheel torque.

For the most part, the interesting thing to look at is the area under the HORSEPOWER curve, not the torque curve. Tim's car has a lot of horsepower available at 3500 RPM. He can shift out sooner because your optimal shift point is where the horsepower for the two RPMs match (the current gear and the next gear) -- since his target next gear horsepower is much higher than on a blower car where you may not have full boost at 4000 RPM, the optimal shift point is lower too. This doesn't have much effect on the acceleration at freeway speeds, because you can be making 400 ft-lbs at 4000 RPM and you're still going to be accerating slower than the car going the same speed but by running 7500 RPM and making 250 ft-lbs (obviously in a different gear).

At the extreme end of this demonstration -- if you had a true continuously variable transmission, the shape of the torque curve would have no bearing whatsoever on your acceleration, because it's only the peak HP that would matter -- the CVT would run the motor at that speed at WOT.

A decent web link with a bit more info on the gearing selection: http://www.allpar.com/eek/hp-vs-torque.html

BTW, The dyno charts I've seen show a set of stage 2 cams will beat out stage I cams at any RPM above 2000... do you really need the torque below 2000 RPM??? You don't use that even in a drag race unless you seriously bog... Obviously the stage I motor is more tractable on the street, since you don't have to keep the RPMs above 1500, but that doesn't make it faster in a race ...

(or perhaps you have seen other dyno charts. I know some people get some crappy stage II cams).


And, to remain on topic, just 6psi of boost across a broad range of RPM would really make these cars a blast to drive -- think of it as having a 40% larger motor -- but one that still breathes well on the top end.

-Lance

 

[jedhead]

Some good points Lance, but some of the drag racers that I have spoken to have made changes to enhance torque and giving up some horsepower. Since the class he is in has a displacement limit, he has changed from a short stroke large bore which gave him more horsepower to a long stroke small bore motor that has less horsepower. Going with the longer stroke he has more torque less horsepower, but the car a lower et and higher trap speed according to the driver.
I will have to find a MTX Stage 2 cammed SHO to experiment with.

Bob

 

[Lance Cheney]

Some good points Lance, but some of the drag racers that I have spoken to have made changes to enhance torque and giving up some horsepower. Since the class he is in has a displacement limit, he has changed from a short stroke large bore which gave him more horsepower to a long stroke small bore motor that has less horsepower. Going with the longer stroke he has more torque less horsepower, but the car a lower et and higher trap speed according to the driver.
I will have to find a MTX Stage 2 cammed SHO to experiment with.

It would be interesting to see what the entire curve looked like from his dyno. If you look at my 'cam timing' chart you can see three curves with different cam timings. The blue and black end up integrating out to being approximately the same for a normal gear, ONCE in the powerband... The smaller torque improvement on the top end balances out the somewhat larger torque loss on the bottom end. However, if I had to start in a drag race that loss below 6500 RPM would be more significant for sure, as it affects 1st gear and -- to an extent -- everything after it since it took that 0.1 second longer to get to the powerband.

Same motor, just different cam timing curves:

I typically run the blue line on the track, though for road-course work I am below 4500 RPM for a decent amount of time, so something in between that and the red would probably be more appropriate. For drag racing I'd definitiely prefer the blue over the red line as it is substantially faster in the 6000-8000 RPM range, where the motor spends most of its time; I lose a tiny bit (avg ~1% from 4000-6000 RPM) through 1st gear, but am up 6-7% at 7500 RPM.

-Lance

 

[jedhead]

It would be interesting to see what the entire curve looked like from his dyno. If you look at my 'cam timing' chart you can see three curves with different cam timings. The blue and black end up integrating out to being approximately the same for a normal gear, ONCE in the powerband... The smaller torque improvement on the top end balances out the somewhat larger torque loss on the bottom end. However, if I had to start in a drag race that loss below 6500 RPM would be more significant for sure, as it affects 1st gear and -- to an extent -- everything after it since it took that 0.1 second longer to get to the powerband.

Same motor, just different cam timing curves:

I typically run the blue line on the track, though for road-course work I am below 4500 RPM for a decent amount of time, so something in between that and the red would probably be more appropriate. For drag racing I'd definitiely prefer the blue over the red line as it is substantially faster in the 6000-8000 RPM range, where the motor spends most of its time; I lose a tiny bit (avg ~1% from 4000-6000 RPM) through 1st gear, but am up 6-7% at 7500 RPM.

-Lance

I asked my friend if I can see his dynosheet, but I got you must be nuts look. He has his engine dynoed on a engine dyno not a chassis dyno.
My dynosheet on a 3.0l with all the bolt-ons except the cat back and the engine is internally stock with 75K miles.

Bob

 

[SHOMurph]

I'll scan TexanTony's dyno sheet tomorrow.

Hopefully someone can host it for me as I iz dum asp en comeputters.

 

[flosho]

SHOMurph, email it to me and I will host it. [email protected]