kgorman

What tuning have people done and actually dyno'd to increase power beyond cat-bypass/exhaust/airbox?

reading throught the archives, there appears to be so much information, and much of it seems like speculation rather than reality.

Anyone have some dyno's runs to show power ~280hp+? If so, what are the mods you did? Obviously superchargers (like TPC) get you there, but I am more interested in other non-sc solutions.

Colin 90 C2

With my current setup the dyno shot is on this link https://rennlist.com/forums/964-forum/213633-modified-your-exhaust-muffler-dyno-results-wanted.html

Do you want ~280hp at the wheels or at the crank?
Of course different dynos display different numbers.

I think that a change in EFI management will get you close to 280hp. Of course, that is not cheap.

kgorman

I guess I was thinking crank, but rwhp numbers are fine too. Someone probably knows the loss for C2 and C4 (I am sure they are different) so we can calculate the rwhp numbers and vs versa.

Looks like that thread is similar to my post, but not many replies.

Colin 90 C2

If you use the search function, there are a bunch of older threads that had some good info. Most of them were about exhaust systems and chips. I think that if you seach for "dyno" you will get some hits.

I can tell you from my experiences, the cat bypass seemed to make a power difference and the chip seemed to fatten up the torque curve. Unfortunately, I did not have enough dyno time to start from stock configuration and make changes, especially since the chip change needs about 15 minutes of run-in time.

I may have my chip available for you to try out in a few weeks as I am upgrading again. I too am looking for real big power increases and I have chosen the forced induction path.

kgorman

yeah, I used the search func before I posted. I just was hoping to see some concensus, the archives are all over the map as to any benefits beyond catbypass/exhaust/airbox.

Tom W

Kenny: If you spend the money to go with a MoTec and modify the exhaust, you can get to about 300 hp at the flywheel (using the stock air induction system). With a 12% loss, that means about 264 hp at the wheels. I was very happy to get about 245 at the wheels with the stock Motronic, the cat bypass and a secondary bypass (with a 12% loss - about 278 at the crank).

The difference of about 278 (old engine cat bypass and secondary bypass) versus 294 (new engine MoTec headers and phase 9 mufflers) was pretty pronounced as measured by where my shift points were at Thunderhill. Shedding an additional 300 lbs and getting to 2500 lbs was even more pronounced.

kgorman

Tom,

As always, good info. Actually out of all of the posts I read, your post regarding using the fabspeed headers, dyno results, etc was one of the most educational.

Thx for the reply.

Colin 90 C2

My thinking was that after the cheaper upgrades ( catbypass/exhaust/airbox), you just have to start throwing money at the car.

Here is what I looked into:

lighter wheels

993 exhaust manifolds (some claim that the increase in power for the 993 engine was largely attributed to the headers, I have heard as much as 17-20 hp, YMMV)

Mass air sensor to replace barn door. some have seen results from -5hp to 15hp

rs clutch/lwt flywheel. less mass for the engine to spin up.

EFI system ( sdsefi. motec, etc) claimed to give 20-50hp on its own, but much setup time. Also infinitely adjustable for future mods.

3.8L conversion/race cams

lightwieght body panels to replace existing heavy steel panels.

Supercharger (TPC, SoK) I have heard of belt alignment problems, don't know how true the stories are.

Turbocharger(s) ( anything from twin turbo engine swap to Protomotive, TTP, Ruf)

There are ways to get more power, it just depends on your de$ire.

Colin

kgorman

Colin 90, thanks for your reply. Your comments mirror many other posts. I was hoping this thread would be more scientific, and have a list of mods and dyno results listed out. That way, all the other 'subjective' stuff in the other posts would be weeded out.

hehe, oh well. ;-).

Colin 90 C2

You may need to start another post and use a heading titled "what mods have you done to increase power and can you prove the power increase"

I know Christer and others have done major mods.

I will be sure to get dyno results once my next upgrades are finished. Hopefully I won't blow up my engine before I get it to the dyno.

Marc Shaw

Unfortunately, the reality is that dyno time does not come cheap and is subject to a few variables.

As has been pointed out already here and elsewhere, to get concrete numbers, you need to put the same car (engine/transmission) on the same dyno under the same atmospheric conditions.

At CDN$85 per dyno run (or CDN$325/3 hours), it is not cheap and gets time consuming to try to measure all possible combinations. To swap parts is neither easy nor quick as DME's need time to adapt to new chips, intakes, exhausts, etc. Plus, the reality is you can't swap out a hot cat. for a bypass pipe until it cools off and....if the clock is ticking on your dyno time....it can make you a bit ant$y.

Ideally, the people selling the stuff we buy would do it but the numbers just get inflated by the marketing departments anyway.

Marc

jeff522

I have an old rodders trick.Using 1/4 mile trap speed.If you know the cars wt,its Cd and trap speed you can est hp.You do need to correct for weather,but its a really good method.Most dynos est hp and torque that why differnt types of dynos give different results.The nice thing about using trap speed vs 0-60 times is it is not so dependent on reaction time.By doing 1/4 mile trap speed one can clearly see if a mod has helped hurt or done nothing.It also gives a much better look at" real world"performance.The big down side is having to have the engine in your car,not always the best for building an engine.While getting peak hp and torque numbers and looking at the curve is nice it can be misleading.(Fellow math geaks will understand about the area under the curve.)While trap speed and to a lesser extent e.t. show how well the car is performing.Spell cheak not working bad for me.When I should have been learning to spell I was building SB Chevys and I'm somewhat dyslexic Jeff

Chris M.

skip all that stuff and GO for it!!

c

Tom W

My $0.02 (and we are all entitled to our opinions).

I've spent a ton of money on my car. Not all of it wisely. Without major mods to the air intake you will not get much more than 295 to 300 hp. My engine and others built to the GTL class rules verify this observation. Christer and other have achieved more, but it's at a not insignificant cost and with more mods to the engine. Sure you can get more hp, but how much are you willing to spend is a question you have to ask yourself (and why). People make all kinds of claims about hp and many (mistakenly) think that changes provide additive hp. I don't believe it. I've never seen any evidence for more than a 10-15 hp gain for exhaust and/or simple chip changes. It's real easy to LOSE hp from changes to the exhaust and chip. Luckily I got some of my money back from that misguided attempt at more hp.

Yes weight makes a difference. When I removed 200 lbs from my car it made a bit of a difference, but it was not profound. When I got down to 2500 lbs, I thought it was starting to see significant differences. Losing 20 lbs by spending $3k for lightweight wheels and expecting it to make a meaningful difference to an othwise stock car is ... silly. While that change might make a difference with a pro driver in a professionally prepared car, I think that duffers like myself have no prayer of feeling or measuring a difference. Don't get me wrong, I think I'm a decent driver - over 50 days at the track in the last 3 years, PCA instructor and pretty good car control - but I've got a ways to go to be able to compete with guys that have 10 years experience and I will never get to pro level. I even hit the apex at one or two turns per lap.

I still believe that the most gains at the track (or lap time decreases) have come from simple seat time and working on the driver, not pissing more money into more mods. For a street car, I simply do not see any point in it.

I believe it's best to spend money on track time. Yes, I just spent a bundle on my car and on the face of it am not following my own advice. I spent the money to modify the car for a specific purpose - to fit the rules for the class I want to race in.

Sorry for the rant. I started out spending money on a search for more power and "faster" mods based on a lot of what I read on this board. Over the years I've come to the opinions expressed above.

Lorenfb

"I still believe that the most gains at the track (or lap time decreases) have come from simple seat time and working on the driver, not pissing more money into more mods. For a street car, I simply do not see any point in it.

I believe it's best to spend money on track time." - Tom W -

Great Post!

It restores your faith in good knowledge based web sites, e.g. Rennlist,
when reality sets in.