333pg333

Guys this is one for the open forum, but I have been looking at what to do next to my car and it is time to look into the engine. Rolex has already given my a very comprehensive list should I choose to stay with 2.5 ltrs and keep costs down. My budget is not defined yet and it may allow me to go up in capacity. If so, I'm wondering just where do you stop? I'm not looking at going all out 3.2ltr 968, but the 3.0 Chris White conversion is a possibility. This involves new sleeves, pistons, rods, crank etc but now I'm thinking of other parts like headwork, intake, headers etc...Firstly I get the impression that Chris doesn't dismiss the stock head, cams, and valve size so therefore is it worth the extra expense? How much extra power can it translate to and does it shift the powerband further to the right? Also can these parts be added at a later stage without too many dramas? John V, if you design a piggyback program for 3.0 with stock top end, can I change to a different head etc later with the same program and just tune it with the Smt6? Rob, you've had different heads on your cars, what do you think of the power delivery. There's a 944 t in the U.K. that has over 400hp which has most of it's mods through Lindsey. There is talk that it actually suffers from a bit of torque loss for such a powerful car and some people feel that it could be due to the new Lindsey intake and head? Is this possible? I am going to change to the race valve springs but what are the feelings of solid lifters?

It has been suggested to go for a 3" to 4" exhaust like the Cup cars. Is the 4" harder to fit and does it drone too much. Can it decrease torque or help to shift the powerband up too high? My car is still a street car so I don't want all the power to be delivered between 5500 and 7000, I want a nice broad power curve.

There's a ton of other stuff as well. I'm open to suggestions. My power goals are in the 450hp area but reliability and broad curve are the prerequisites. Because of being in Australia and suffering the tyranny of distance, my thinking is to do pretty much everything right the first time. It's too expensive to ship parts back and forth on a trial and error mission. So when we go in it's to do a complete job or as close to this as possible.
Thanks for any ideas,

Patrick

333pg333

50 views and no opinions? C'mon guys, yes I know "Search is my friend" but it can take a long time to sift through everything and find up to date info. Some of you must have tried and failed or succeeded? Is it worth the money to do headwork for example which in turn leads to intake which in turn leads to yada yada yada?

Chris White

Seems like the guys figured it was a ‘big bore’ and fell asleep!

Obviously you know my feelings
How about the rest of the list – lets base the question like this – we will assume that the 3.0 (using a 2.5 block so that the 2.5 head will bolt on) is a base for the project – Can you come up with what you would add to that (in order of importance) to make up a nice engine? As always in the real would – cost has to be factored in to come up with the order of importance!

Chris White

Tom M'Guinn

Well...my street project involves the following:

89 Block bored to 104.5
Mahle 104.5 turbo pistons
Carrillo Rods
Stock 3 liter crank
2.7 head, 951 exhaust valve/swain ex-ports/minimal port work
951 intake with ports recontoured for 2.7 head
probably 951 cam, but will test drive a VR cam for streetability
stock headers
stock intercooler, but considering LR-like end caps
VR stage 5 turbo and MAF/chip board
83lb injectors
trusty Profec B boost controller
3" exhaust (with stock muffler)
Tial 46mm WG
Still shopping clutch/PP options
Not enough time to bolt it together and stuff it in

333pg333

Tom that looks like a very nice list for your project. Should be a quick car when you're done! I would have thought a larger i/c would be of benefit? The 2.7 heads are getting rarer and more expensive. What do you know of their benefits v's say an aftermarket one sold by one of the reputable vendors? I guess as Chris W has said to me it's a case of diminishing returns. You can put together a good basic project and after that the extra horsepower starts to add up $$$ exponentially.
Chris, I'm obviously looking at doing one of your kits and adding a new larger turbo w larger inj., fuel pump, exhaust etc. Things like intakes, heads, extractors/headers, etc are of an unquantifiable benefit to me as I have no experience in one v's the other. So I am relying on other R-listers experiences to help put that list together. So if someone says that they got an extra 40hp by putting on a new head with larger valves, port and polished etc and it cost them a total of $3000 I would have to think whether that's worth it? As I said the budget will be more than just a basic upgrade so I'm open to what others have experienced.
Thanks.

Chris White

The problem you may run in to is that most folks do a bunch of mods between tests so it is hard to quantify the results of each change. In addition to that you will also find that some folks may have done some mods that didn’t make much difference until the last mod made them work – example – add the SFR stage 2 headers to a stock turbo and then change the turbo later. Most of the real gains of the headers weren’t noticed with a K26/6 but once you add a good turbo the headers will make a big difference.

So – take what you here with a grain of salt!

On the header note – I don’t think the SFR stage 2 headers will fit a right hand drive…and that’s a shame – I would have out those on your list.

On the 2.7 heads – remember that the reason these were a hot upgrade is that they allowed you to bolt turbo parts (intake and exhaust) directly on a 3.0 block, now we have ways of increasing the displacement of a 2.5 block up to 3.0.

Chris

333pg333

Thanks Chris.
On the subject of headers and this is going to sound pretty stupid, but it seems that the prerequisite is that they're of equal length and of good materials with good workmanship. Now obviously they have to all flow nice and evenly but is that the hardest part? Making them flow evenly. What I'm getting at is if there is no way that something like the SFR headers can work for a rhd car, then couldn't some local guy down here fabricate something that would be a reasonable facsimile? Surprisingly there are some good engine builders and fabricators down here. Or is it too hit and miss?

Tom M'Guinn

Other than the LR end cap trick, its hard to upgrade the intercooler without relocating it (in front of the radiator like SFR) or cutting the crossmember at the front of the car (structural surgery). That CO2 spray system keeps catching my eye -- it super-cools the i/c by venting compressed CO2 on it.

As for the 2.7 head, as Chris says, it gained popularity because it works on a 104 block AND with all the factory turbo intake and exhaust parts. Also has bigger intake valves and no ceramic in the exhaust ports (so, unlike the 951 head, they can be ported). Wich Chris' MID system though, you can nicely prep a 951 for the price of a 2.7 core... If I do another motor, I'd seriously look into Chris' system.

RKD in OKC

Patrick,

I'm rebuilding my motor this winter and plan to do a 2.8 stroker. LR has a 2.8 stroker in their shop now that is making over 400 rwhp at 15psi with only a sport turbo.

Tom M'Guinn

Impressive. How's the torque curve? Wild headwork and big cam?

RolexNJ

- I think I know the guy you are talking about, it has nothing to do with headwork. Non-issue. He was having injector problem. Anyway, if you get the LR intake, you are going to shift the TQ to the right. That manifold is designed for more mid and high. And unless you've changed your goals, that isn't what you want Patrick?

The graduated 4 inch system from LR. Much debate here. For me, I felt a difference by the seat of my parts. Also, for what it's worth, they were used on Cup Cars, many people don't know that. Three, it is a bit tighter, but the installation is fine. I have 2 other friends of mine who did it too. The people who will "maximize" the most of a graduated system are poeple making some pretty big RWHP. But others can gain from it too. And it will not make the car sound different than a 3 inch alone. BS. I had both on. What makes the difference is the cat/or no cat, and which muffler you choice. Anyway, take a look here at the Lindsey Comparison Chart and see what they found out.

-Solid lifters? Again, for what you are doing Patrick, I would say definatlely no. Unless you are looking to reduce valve train weight, and rev a bit higher; the cost and ongoing maintenance isn't worth it. Plus, not sure if you care (I do), you will hear the vavle train noise. Will sound more mechanical coming from under the hood. Stiff springs? I would look into that if you plan to run higher boost. Lindsey makes some great Racing Springs that are better for long term with respect to running higher boost.

Hope that helps. In my email, I had addressed a lot of other issues that I'm not going to go back into here.

Tom M'Guinn

I've never been convinced that there is a need for stiffer springs solely as a result of higher boost.

RolexNJ

Ok pal, you got it.

JET951

well i guess stiffer valve springs would close the valve quicker(thats if there is valve bounce present). and i guess if you are running high boost, say 25psi, then possibly the pressure from the boost could hold the valve open for fraction of a second. i would say extra revs would be more of a cause of valve bounce

RKD in OKC

LR has data from a cam provider that modeled the 944 valve train. This model was done to specifically determine the spring load needed to operate different cams. Their findings were that the factory stock cam, hydralic lifters, springs and valve sizes float at above 16psi of boost. This makes sense to me that Porsche would engineer the springs to be just enough to make the valve train as efficient as possible without floating. Operating a valve train uses some of the power from the motor. Stiffer springs use more power.