boring and intake manifold??

XxKHxX · 06-04-2005, 03:08 PM

I have a porsche 944 84', and was wondering if boring the throttle body and or the intake manifold would produce significant changes in my performance? Would it be worth it? If so, where could i go to get it done? or send it in...

btw...i read somewhere that after you install a bored manifold/ throttle body, you need to reset the computer? is that only for newer cars, or does that apply to an 84? Thanks

SoCal Driver · SoCal Driver's Garage

Larger throttle bodies don't make any difference in performance for a naturally aspired (non-turbo).

If you want to flow the intake ports and match them to the intake manifold you will find a bit more performance.

You can change out the mechanical AFS (air flow sensor) to a heated element (MAS) and see a bit more performance. FR Wilks is getting ready to market a reasonable cost unit.

You can get a cam off of an 85.5 or later engine and get a few more horse power from it's longer duration on the exhaust.

As you are a new member here and possibly a new owner you really need to check your timing belt or just replace it if you don't know it's history. Timing belts last about two years or 30,000 miles.

If you have the rubber center clutch disk you might think about replacing it with a later spring center disk.

Otherwise put your money into the suspension and tires.

scheistermeiste · 06-04-2005, 04:06 PM

and dont ask how to put a turbo on it, if you want a turbo its cheaper to but a 951

AznDrgn · 06-04-2005, 06:09 PM

Quote:

Originally posted by scheistermeiste
and dont ask how to put a turbo on it, if you want a turbo its cheaper to but a 951

LOL. That should be a part of the rules for posting " If you own an NA don't ask how to put a turbo on it, if you want a turbo it's cheaper to buy a 951".

DannoXYZ · 06-04-2005, 06:37 PM

We should make it a sticky and put up that picture I scanned and the parts list with pricing. Then the only guy I know of that's done that job can put up a step-by-step procedure (over 100 hours of pro shop-time, count on 150-200 for home-mechanic)...

PhillysMostWntd · 06-04-2005, 08:12 PM

i have my intake manifold bored 3mm over, most machine shops have the tools to do it, 3 angle bore is the most common i believe, throttle body is bored too.... but now i find out no change?

that sucks, but yeah it doesnt feel much different with the over-bore

AznDrgn · 06-04-2005, 08:46 PM

problem is your motor doesn't breathe that much so you can open up the intake and TB all you want and not gain a thing.

SoCal Driver · SoCal Driver's Garage

Not a problem. The NA engine was maxed out by Porcshe to get as much as they could from the package for the time.

So you can add HP but at about $500 per up to maybe plus ten. Best improvements are higher compression pistons (requires a knock sensor), a cam (don't beat the valves into the pistions) and a better programmed chip in the DME (smooths things out).

scheistermeiste · 06-05-2005, 07:09 AM

ya know i think thats why there isnt as much interest in the N/A 944 as there are in other cars, its sorta cool tho that back then porsche was able to enginer just about every availible HP out of the engine they could that long ago

fast924S · fast924S's Garage

I dont believe that the NA engine is maxed out, there are ways to make HP and it will cost money, But to make any 4 cylinder make good HP cost money. No production engine is maxed out in HP. The car company has rules they need to follow, It has to be fun for eveyone and it has to be made so eveyone can drive it, they have a tight buget to follow, they have to follow emission specs and also company politics play a good part too. Most people would rather buy a turbo or buy a bigger engine, because its easier to make power like that. The biggest problem is people think that just doing one or 2 things is gonna make 100hp. Its not about a bigger t-body, or a MAF upgrade, its all about the HOLE PACKAGE, What are you build the engine to do, What kinda HP do you want, Where are you going to be driving the car, How do you want the car to feel, all play into how you build the car. If you looking for MAX NA HP, then you gotta do a ton of internal work, like Boring, upping the CR, Porting, Head mods, DME mods, ect. But if your looking to just add maybe 20hp, get some headers, a chip, a Cam. The only other real way to add power is with Power adders, like nitrous, SC, turbos. I dont believe any engine is maxed out, there is always more to be had, its just about how much you wanna spend and how much you know about what your doing

DannoXYZ · 01:04 AM

"The NA engine was maxed out by Porcshe to get as much as they could from the package for the time. "

"I dont believe that the NA engine is maxed out, there are ways to make HP and it will cost money"

Well, you would do the exact same things that Porsche did to get more power from those engines. You have to upgrade the technology used, not try to push the existing technology further. That means you can basically swap in parts that Porsche spent a lot of time,money and R&D on. You would basically evolve your engine into a modern Porsche engine with:

- add 10.6:1 compression Euro pistons
- even better, add 3.0L crank and bore out to 104mm pistons
- add 4-valve S2 head, or even better 4v 968 head with VarioCam
- add variable-geometry intake-manifolds, variable exhaust manifolds
- replace AFM with MAF from 968 with matching engine-harness and DME
- add VarioCamPlus or other variations like SuperVANOS, VTTI-L, etc.

In an NA engine, the most important factor is the resonance-tuning and frequencies that are optimized due to the specifications of the intake-manifold runner lengths, their diameters, the plenum volume, the valve sizes and shapes, the port volumes, the cam-specs, and the exhaust-manifold dimensions. All these factors combine to form a range of RPMs with the higest VE-volumetric efficiency. You have to juggle ALL of those factors in consideration of the rippling effect it has on the remaining components.

So... if you want more power between 5000-7000rpm, you'd change ALL those specs a certain way, which would sacrifice power outside of that range. Or if you want maximum-torque beween 3000-5000rpm, you'd pick some other specs for ALL those components. But there's no one part, no one specification of anything, that'll give you better performance across the board. You have to change ALL of those components in concert with each other. And even then, it's a series of compromised configurations, you just pick the one that works best for the kind of driving that you're going to be doing.

Nothing's impossible, I can build you a 250rwhp 944NA engine (double stock HP), for about $30K. It can be done, but this will be a race-motor that's usable only between 5500-7500rpm. Or you can buy a TurboS with chip-kit for the exact same output across a more usable 3000-6000rpm range for $15k.

herdman · 06-06-2005, 08:31 AM

I agree with Fast924s and Danno. The 944 engines are well developed at Porsche. Looking at the T-body and intake man., they are "about" maxed out . I have done some up grades an some other engines and am amazed at what leaves the factories of other companies. I guess that is one reason there are so many aftermarket parts for Fords and Chevys. You can deffenty get increases in perfomance by gasket matching and porting intakes and heads from these companies. I cann't believe how restictive they are! But take a 944 engine appart and it is apparent that thought and enginering went into their manufactoring. Like Danno said you can get gains but at a high cost on return. Stick to a few "Tried" and proven upgrades both in engine , brakes and suspension and you can tune your car to perform to your individual taste. One thing that hasn't been talked much about in this forum is the other factor in reaching max perfomance from you car. And thats driving skill. I think most of us could benefit from a few days in a driving class at the nearest race track. I know I'm going to be one of the first to sign up at the new road course coming to Utah this fall.