*eurospeed951*

So, I’m just doing some thinking about the limiting factors in the performance of our engines. From what I understand, once a large enough turbo, injectors capable of flowing enough fuel, and a less restrictive air metering system have been added, the next limiting factor is the flow of the engine. I would think that the 4 major areas that affect this are the: head, intercooler, exhaust, intake manifold. From what I have heard, the area that would provide the most improvement in flow would be the head, then intercooler, exhaust, intake manifold. If this is so, I would think if you were trying to improve the flow a 16V head would be the first place to start.

I know that this is done, but what are the different ways to achieve this? If anyone reading this has done this, what was the price rang?

I have no plans to do anything like this yet, but I have some time now to research and would like to hear any info you all could provide

BoostGuy951

I think the exhaust is more restricive than any of the other parts you listed. I am also not sure that stock for stock the 16V head flows any more than an 8V head. There is no power difference between a 8V 944, and a 16V 944 S.

Jfrahm

I thought the 16v head flowed a lot more than the 8v. To swap onto a 2.5l 951 block, you'd want an 'S' head. I don't know what you do about an exhaust header but for the intake you can cut up the 16v and Turbo intakes and mate them together. You might also consider a sheet metal intake.

-Joel.

Sami951

Huh? The 16V S makes 30 extra horses compared to 8V N/A, plus the power is higher up in the rpm range, something the 951 usually lacks...

I would personally love to know why modified 951s seem to drop torque right after 5000-5500 rpms (TonyG excluded of course ). Is it the intake manifold, exhaust, head or the restrictive turbos (#6 hotsides and such)..?

TurboTommy

eurospeed951;
Have you done your exhaust? It's not in your sig, but that's the first thing (after the turbo). I'd assume you changed your exhaust (not headers) because you've also done other mods. After that, along with the other things you've said, it's a toss up between the intercooler or headwork. If your turbocharger hot housing is big enough, I would do the head (camshaft mostly). If your hot housing is borderline the intercooler should be next. The intake manifold doesn't do much; some would disagree.
If you're contemplating a 16V head; not only is it a good place to start, it's the ultimate setup. But it's big $ if you want to do it right; others on this list would have more details on this.

*eurospeed951*

what makes the 16V head big money?

mslovak1

euro,
The 16v head should flow 1.5+ times as much as the the 8v head.

I think the costs comes in steps:
You have to find the head, usually attached to a complete engine purchase, (unless you have a 944S2 or 968 already)

New valves, springs, possible porting, and then ceramic coating.

Now what to do about the turbo'ing of the engine: Pistons, sleeves.

The intake mod's, as mentioned above, can be done by marrying a 968 & 944T intake. I am going to have this done by Tim @ SFR for my project. Possibly not ideal, but well suited to a stock look.

M

*eurospeed951*

thanks for the info mslavok1!

Anyone have any data showing the flow numbers for different 944 heads?

What affects will this increase flow have?

Are there any other ways to get a 16v head, like can a 8v turbo head be made into 16v, or are there any other 16v heads that could be modified to work but would alow the use of the stoke intake manifold?

Thanks for helping me with my research. I want to gain as much data as I can before I start my engine rebuild 2.0!

*eurospeed951*

bump

BoostGuy951

What about the 2.7 NA head? How does that stack up to a 16V head, I wonder?

rage2

Here's an interesting question. If octane wasn't a factor, is there any difference in turning the boost up instead of increasing flow to allow more air at a specific boost level?

*eurospeed951*

GREAT QUESTION!

Anyone have any info on this?

I'm not sure how it would effect me exactly, because I know I want to build my car to run on pump gas.

let's keep this thread going

Alan C.

If everything stays the same and you just turn up the boost you will have a hotter intake charge. Less boost and more flow should result in a lower charge temp

Alan C.

*eurospeed951*

good point

Sami951

Wouldn't it also depend on the compressor used? With a really small compressor, keeping the same boost but increasing the flow (like with a 16-valve head or something) would probably force the poor turbo to work a lot harder -> out of efficiency range and lots of heat again. No?