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Old 02-21-2004, 06:06 PM   #18
SAAB Road Master
Join Date: Feb 2004
Posts: 361
Originally Posted by Tweek's Turbos
Ok Adrian, Lemme mention I also have a Garret T-28 with newer style curved blades instead of the T25s straight blades.

Lemme see here. What I want to do is,

Get a Viggen Head, or at least a Ported T5 head. With viggen Valves.
Cams from a NA 2.3
Exhaust header say, from Taliaferro.
Is it safe to backcut the nimonic valves from the VIggy?

Mind you this is just talking general head work. Can you recomend a good headgasket? maybe something copper?

I plan on sticking with the Propane injection, as it has better reviews than alky inj for the turbo buick crowd, and dont think I will be using a water sprayer. However I did see one on an STI a buddy looked at and thought it was a novel idea.
As for the propane injection, that's up to you. Typically cars have trouble getting enough oxidizer into the engine, rather than not enough fuel. (Propane is just a another fuel, no better than gasoline.) You'd get more power with Nitrous Oxide, and some extra fuel from your standard fuel system than you would with propane. Both will run out when the bottle is empty so I don't see any difference in that regard. It's just another trick to get horsepower for a few seconds at a time.

Ok well here's the breadown of the "red" questions:

Ported T5 head will be much cheaper than a T7 head. With the extra money you saved you can get some things ceramic coated. Cermic coating the exhaust valves is better than getting the Nimonic Alloy 901 valves from the Viggen. Though both is better still. You'll also have enough to Cermic coat the pistons, intake vaves, and exhaust manifold if you choose not to get the headers.

As for back-cutting nimonic alloy valves I would reccomend against it. Nimonic is a very tough alloy, but it's NOT steel. It's a nickel alloy, with a very complex composition. Probably best not to do anything to it unless you're sure what you're doing.

I want to reccomend again ceramic coating the piston tops and exhaust valves. These are the two primary weak points in most turbo engines. Getting them coated with significantly reduce the heat absorbed by the engine. The less heat that is absorbed, the more goes into powering the car! The exhaust valves just need to be coated so they can take the heat for longer periods. If you refuse to get them coated, Nimonic is better than standard Stainless, but coating them will certainly increase their durability.

To get some performance coatings, in case you wish to spend some more on various other things that can be coated, go here:

When I get a chance I intend to coat the heck outta my Viggen's motor. A turbo engine is basically just an efficient hot gas generator for your turbine (the turbo) ... so how you manage that heat is very very important to how well you power that turbine. The performance coatings are all about heat management, and lowering friction. Both of which make the motor are more efficient hot gas generator. *big thumbsup*

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