seattle951

Whe I am looking at other Rennlister's dyno charts their TQ numbers are usually higher than their HP numbers. My 951 is the opposite.

My 951 dynos 316 RWHP, 306 RWTQ at 17 PSI. Looking at Nize's recent post, he pulled 324 RWHP and 334 RWTQ. Both are (were) 2.5Ls at the similar boost. My car was dyno'ed on a Mustang Dyno and Nize's on a DynoJet.

Most of the dyno charts I have seen on Rennlist are similar to Nize's.

I have a long list of of modifications and pretty much everything on the Lindsey Racing parts list. Turbo is a Garrett GT30R double ball bearing.

What engine components tip the scales between HP and TQ? If I wanted more TQ what types of modifications should be done? For more HP, what modfications should be done?

If I am not mistaken, different intake manifolds and head porting optimize the powerband for mid or high end in muscle cars. I am assuming that the same holds true for modded 951s.

At this point I am please with my car and don't plan to make changes. However, I was just wondering how the system works.

blown 944

Post the sheet with AF and if possible boost pressure

One thing I can think of is that if you are using an EBC that is set with extended boost onset that it can be delaying the boost until after the engine is starting to make HP

It also could be a bad wastegate.

seattle951

I posted the dyno chart on another discussion. https://rennlist.com/forums/944-turbo-and-turbo-s-forum/429436-lr-super-75-8-vs-garrett-gt3072r.html

Tms951

If you make good torque down low but it dropps off up top you will make more TQ than HP.

If you have a well put together engine that has a that has a turbo that is efficient up top (gt30r) your torque is not going to drop off up top and You will Make more HP than TQ.

What you have is a good thing, what Nize has is not. What this means is your car keeps on pulling his does not.

ehall

"What you have is a good thing, what Nize has is not. What this means is your car keeps on pulling his does not."

That is a totally ridiculous statement!
People pick turbos to fit the way they want the car to perform. nize has built a street car. He's not some ******** kid who drives 150 mph on public streets. His car is set up to give him the quickest and earliset real world torque that he can. In the real world, on a street car, what happens over 110 mph is irrelavent.

seattle951

Any feedback on my original queston about components optimized for TQ or HP?

I was looking through a book on the history of muscle cars and they showed some of intake manifolds created in the 1950s to increase TQ. Some of the more exotic designs had the carberators a good 18 inches from the engine on the left and right hand side of the engine compartment. My 951 uses an aftermarket intake manifold that seems to use the opposite philosophy and has shorter runs than the stock 951 intake manifold. Nize, for example, retained the stock intake manifold.

Perhaps, has this manifold changed the system optimizing the engine for HP opposed to TQ? I have aggessive porting on the head. How does that affect the power bands?

Jeremy Himsel

Different dyno's could be the difference and Nize's posted charts were uncorrected while standard charts, what most people do, are use SAE corrected charts. Getting AF ratios right in a 951 chip isn't a hard thing to do but plotting a timing curve applicable to you engine or specific application is critical for making power. Dead nuts A/F curves and a vanilla timing curve will limit power and leave a bunch of tq on the table.

If your happy with it then don't worry about it. Dyno it on a Dynojet and use uncorrected numbers if you want to feel better. Talk in depth with your chip tuner about your timing curve. Post some more info about your mods if you want more advice. At those power levels another intake will yield very little gains. Where are you seeing 15psi in 4th gear?

seattle951

My car is set up with Mafterburner and the A/F ratios are set with a PC on the dyno. I am traveling and don't have he A/F and boost levels with me to go along with the dyno chart. However, they are very smooth thanks to EBC and Mafterburner software. The shop that tuned the car did suggest that Mafterburner had limited granularity and the mixtures could only be tuned to a range. However, the car runs at 14.3 to 14.7 off-boost and 11.2 to 12.4 on-boost. The car does awesome on emmission testing and runs very clean.

Below is what has been done to the car by a shop in Washington.

2.5L motor with 5k miles since complete rebuild
Garrett GT30R double ball bearing turbo
3 inch Lindsey Racing exhaust
High flow catalytic converter (chose to lose a few HP to be green, car passed smog without cat)
Dual port wastegate
Lindsey Racing Intake Manifold
Lindsey Racing MAF
Cold air intake sysetem (custom)
#52 lb injectors
Lindsey Racing Stage II head
Lindsey Racing Stage III Intercooler
Lightened, knife edged, cross drilled crank
Pauter rods
100.5 pistons
Aluminimum flywheel and lightweight clutch assembly
6 speed LSD transmission
Lindsey Racing Chips
Mafterburner software
Electronic Boost controller
Additional oil cooler
No air conditioner, no sunroof and manual seats (from factory)

I have probably forgotten a few parts.

Anyway, the muscle car book peaked my interest and I was wondering how my choice of upgrades skewed the HP/TQ ratio. As I said, the car runs fantastic and I don't plan to change anything.

TurboTommy

Well, I don't 100% understand your question, but if you want justification for why your hp is higher than torque, I would say that the modified manifold and head definitely are reasons for that. So, if you're happy with that powerband, I would be rest assured that it's normal.

ehall,
I would say that tms951 is right; that the higher power band is the faster car, and what you do with that power is up to you. Saying that anything above 110 mph is irralevent, is a bit silly

blown 944

I still believe your EBC is set to delay the onset of the spoolup therefore it isn't hitting as hard early on in the rpms also delaying torque until later when torque diminishes naturaly with these engines VE.

What you are reading in the the older magazines is very correct with longer runners being more for low end and shorter top end but with boost that is a totally different story. The velocity of teh forced air is much higher and somewhat negates the need for any reunner concern unless you are trying to get eh absolute most out of the setup (high HP).

ehall

I'll clarify. For a street car, a person may want the quickest possible spool up, so they will choose a turbo that dies a bit up top as a compromise to a larger turbo that doesn't spool quite as fast, but holds, and creates boost better. A race car is seldom in a range under 3k rpm, where a street car isn't above 3K rpm for more than a short period, due to traffic, laws, roads, etc.
So one may choose a turbo for specific characteristic. That being said, one turbo is neither better nor worse than the other. It all depends on application a goals.

95ONE

Seems like a long list of parts for just 320hp. Did they tune it to higher boost levels and turn it back down, or is 320 all you wanted?

And you could have what I had at first. A slightly slipping clutch not giving tru peak torque numbers (Exactly where it would slip the most)

seattle951

What sort of power would you expect from this setup?

This car is a weekend toy and is virtually not driven. In terms of expectations, I want a reliable, non polluting, well behaved car with as flat a TQ as possible. Except for the TQ curve, the car comes pretty close now. Oil consumption is absolutely zero even with a hard day at the track (DE days). However, if there is some fault in the implementation and power has been left on the table, I would like to recover it. This hobby for me is about the engineering. I prefer newer cars with all the bells and whistles as a daily driver.

The clutch is a Stage III or V (can't remember) and should hold to 700 hp. It is almost new. Other mods I forgot to mention are a 3 inch downpipe, aftermarket FPR, LR fuel rail system, high volume fuel pump.

Everything is new on the car from the suspension to a carbon fiber body front end. The only exception is the wastegate. This was a used LR unit that came with the car. My mechanic felt it was in good shape and we decided not replace it with a new unit. The WG was mentioned in a previous post as a suspect. Should this be investigated?

One note on the seat of the pants dyno. On the last 2 DE days I shared an instructor with other 951 drivers. The other 951s were modified as well, one was 2.5L K26/8 and the other was a 2.8L K27/8. The 2.5L claimed 340 RWHP and 2.8L claimed 420 RWHP. According to my instructor, the other 2 cars were not performing anywhere close to my car. (However, my car weighs 500 lbs less.) I suspect the choice of dynos has something to with the metrics.

On final note, the car does break traction sometimes on the dyno. I have 285s in the rear. Maybe there is more slippage than I realized.

Any input appreciated. Thanks.

seattle951

Back to my original question about optimizing for TQ or HP. I was researching Buick Nailhead engines from the early 60s. The name "Nailhead" came from the small valves used in these large displacement V8s (up to 425 ci). The heads in these engines were restrictive in terms of intake and exhaust flow. When Buick created the Nailhead they were interested in high TQ to move a very heavy car. HP was of little interest to them.

From Wikipedia "The small-size valves and intake runners made for engines with a lot of torque, with many exceeding one foot-pound per cubic inch, which was exceptional for the day."

My question is to group is "With my high flowing head, intake manifold, and MAF, have a created the reverse configuration of the Buick Nailhead shifting the TQ/HP ratio?"

I have a 4.6L Mustang and read about supercharging solutions. There are many different intake manifold configurations that optimize the powerband for either the midrange or highend but not both. Is something similar going on in the 951 mod world?

Second question, using a lower flowing head and manifold increases velocity. What is the relationship between velocity and TQ?

reno808

get your money back