lart951

I bought a car that had the goodies, SFR headers stg II, SFR test pipe, SFR x-over pipe, SFR down pipe, LR race fuel pump and LR Polished super 61 to4e. Next week I will be trying 380rwhp @ 21psi

toddk911

"Ahh, the wisdom of the internet!"

Actually the wisdom of Zotz Racing. A Porsche shop and race team here in Orlando. They also run in the Rolex series and have many SCCA race wins and experience.

Huntley head?? Where is Huntley?

I guess you should call John at VR and tell him to stop working on his head/cam. We all know how John loves to produce parts that offer very little gains over stock.

My point was also more in the head and cam being matched.

toddk911

"The stock head (intake) flowed around 230cfm at .470” – pretty good, on par with aluminum race V8 heads. The exhaust was 190cfm at .470” – quite good."

Try 300cfm+ for performace V8 head intake and 210+ exhaust.

WesM951

This thread is starting to get intersting now!

Chris,
Thus the reason I said minor headwork. I have yet to see major improvments (i'm talking ones that are worth the cost of the upgrade) over stock, VR's sledgehammer head did some good coupled with his cam. What would you suggest for top end work?

What about the stock intake mainfold? Do the LR or SFR parts really help that much?

Chris White

Excuse me Todd, I bow to your expertise. It seems you do know it all.


In case other folks might want to learn something - here is a link to a database of large port aftermarket cylinder heads… http://www.chevyhiperformance.com/te...98/index6.html

Now look at what those heads are flowing at .470” of lift. Gosh, its equal or less than our stock heads….

There are some gains to be made….but not gains that “REALLY opens the motor up”. The intake ports are not “Very restricive on the intake side”, they actually flow quite well. Can they be modified to flow more? Sure, but not a huge difference.

Incase you were wondering, John and I have been comparing notes and the reason for measuring up the flow on the heads is to make up a big valve head that will work with John’s cams. In fact I just installed one of his 007 cams in the 2.75 liter motor to test at Watkins Glen this weekend.

Final note – if you want to do some head mods with the sole purpose of making a lot of HP then modify it to shift the power band higher. Lighter valve train, different cam, head work and such. You can make more power…..but it will suck as a street engine and you will get used to replacing valve guides at regular intervals.

Have a nice day, I have to finish loading up the car now.

Chris White

Chris White

After a little reflection while finishing up my car for the weekend – my apologies – I believe I was a little harsh on Todd, too many brake cleaner fumes and not enough sleep!

Chris White

Eyal 951

I am assuming most of my gains in my head work are in the back cut and fully radiused valves and seats. When Danno did my head, he did D-porting. I don't know what the benefit is, but it looks fast (lol) Its not ported all the way through, but the intake manifold is port matched. Though I kinda regret doing it now, i had it milled .050 (on Danno's recomendation) to increase CR a bit. I think I gain the most HP from my titanium valve retainers. Each one is good for 7.29HP each!

toddk911

Hey Chris!

No problem. How did your car run over the weekend?

tedesco

This was stated at the beginning of the thread:

"63trim flows 75lb/min and is a 67mm Compressor Wheel. (basically a T04R shoved into a T04E housing ) For comparison's sake.. it flows 1088cfm at 1 bar"

That is the LR Super 75. I know it is 67mm comp wheel and mine is #8 hotside


I have got the Super 75 turbo installed on one of my 951s as well and I can guarantee that the compressor- as well as the turbine sections match the GT35R pretty close. That means:
compressor inducer 61mm, exducer 82mm. I would expect to see less lag on the GT35R and I will try this one soon (it did not arrive jet).
I do get boost at around 4000rpm depending at the level I set. Considdering the redline is at 6500 it might be laggy for some, for others it is OK. If you want to make power you have to accept lag (if you are not playing tricks). Other option is, as suggested, to go to higher rpm but that means lag too just achived in a different way. To use the higher rpm you need a turbo that flows more too which normaly would also be bigger and more laggy.

Interesting pictures of the portwork that were posted. To me it looks a bit strange to open the lower part of the ports. In this way I would expect for the flow in this area to go around a tighter and sharper corner to arrive at the valves. I thought rather the opposite direction to be beneficial which would tend to "straighten" the flow in the ports (increasing the roof of the ports in height and width). This would also result in a less inclined flow in respect to the valve stems, one of the biggest restrictions in the ports. The target for good flow I understand in useing the valve circumference equaly for the flow, or at least as similar as possible. Anyway I do not have experience in porting 951 heads. PLease correct me if I go wrong...

Porschefile

Wow. It sounds like the Super 75 is basically the equivalent of a T3/T67 hybrid, which is a BIG turbo. This link will give you guys a better idea of what I'm talking about T3/T67
IMO, that's just too large. It seems a little excessive to use a 600+rwhp capable turbo to meet a goal of 400rwhp, unless you ultimately plan to actually push 600+rwhp. The gt3582r (gt35r) is similar in power output, although the compressor wheel is slightly smaller, and a gt35r should theoretically be a more responsive turbo then a Super 75 judging by the compressor/turbine sizing.

Wes, I'm not sure what your plan is for tuning/engine management. I highly recommend that you invest most of your funds in the turbo, engine management, and head. Your cam, turbo, and engine management are 3 of the most vital factors that are going to determine your powerband and the overall nature of how the motor functions. From the flow bench #'s I've been seeing of 951 heads, they appear to flow pretty poorly compared to more modern DOHC 4cyl head designs. I would say out of all 3 that engine management is the absolute most important. With a good quality aftermarket EMS, you'll be able to fine tune more parameters more accurately than with the Motronic, which will get you that much closer to 400rwhp on pump gas. That's not to say that Motronic sucks, as VR has more than proven it's versatile capabilities when tuned properly. However, with the advancements in technology over the last 2 decades, it's amazing the things that are possible with newer EMS setups. Efficiency is the key. Hehe, or you could make up for inefficencies by doing the classic bandaid of throwing on a massive turbo and beating the engine to submission with huge amounts of airflow! Water injection would definitely be something to look into as well.

Chris White

New stock lifters suck. A two day old lifter started to misbehave after one session – so no real testing results. I am tempted to go to solid lifters just to toss out the stock ones. Either that or I will finish up the 3.1 16v motor and drop that in.

Chris White

tedesco

Maybe it was misundertany but i could NOT measure any difference between the LR S75 turbo and the gt35r on the compressor and on the turbine wheels (diameters and trims). I can not see any reason why the super 75 should be more over the top than the gt35r (leaving the exhaust housings out of the equasion). The reason for me to try the gt35r is the baal bearing centre housing. I can live with the lag that come along with the turbos (anyway a 2.8l and a 3L engine are on the shelfe just waiting to be used).

tedesco

one point to EMS. You can go one way by upgrading the motronic to support all functionis you might need:
- boost control
- fuel piggy back
- ignition retard
- chips
- MAF

All these items cost considderable amount of money. A stand alone EMS can do all of this in one unit and is more flexible in use. So in my eyes an aftermarket EMS is the cheaper way when comparing prices of the components only. The tuning and setting up of the EMS is a different story. Modern EMS often offer the fuction to set a desired air/fuel ratio map that, in a self learning mode adjusts fuel (with a wide band). Ignition would still need to be done separatly. A possibility I see is to take over the motronic settings as an initial set up. This leads to a "working" setup which can form a base for tuning. Previously I used all the piggy back stuff. For the next car I will try stand alone. The difficulties will be in the details...

toddk911

"New stock lifters suck. A two day old lifter started to misbehave after one session – so no real testing results. I am tempted to go to solid lifters just to toss out the stock ones. Either that or I will finish up the 3.1 16v motor and drop that in."

With solid lifters you could run a lot more boost and revs correct? I.e. less concern to float them.

toddk911

"I do get boost at around 4000rpm depending at the level I set. Considdering the redline is at 6500 it might be laggy for some, for others it is OK. If you want to make power you have to accept lag (if you are not playing tricks). Other option is, as suggested, to go to higher rpm but that means lag too just achived in a different way. To use the higher rpm you need a turbo that flows more too which normaly would also be bigger and more laggy. "

How is it possible to squeez out some more revs from the motor?

I agree, lag is an issue, but when I was on the dyno it had a almost perfectly linerar hp/tq curve and was making hp still at redline. If I could safely squeez out another 500rpm or so I oculd add a little to that area under the curve.