Exhaust recommendation for Spec racer Options

[consolidated]

A group of us in Texas are starting a grassroots Spec 914 race series. It's a low key, low cost (yes, I lie to myself often) race series among friend-emies.

I race a Spec Boxster in PCA/NASA and also have two seasons of Chump/Lemons in our "hippie 908" 914-4, which was the inspiration/sickness for these new builds, but otherwise have little knowledge of 914's and asking for suggestions after doing much reading here.

What exhaust do you recommend? My car is a 75 914-4 1.8L ( all cars will be 1.7/1.8L) and I'm considering Triad and Bursch but unable to find much info on SSI or Thunderbird (recommended to me). This is a race only car so HP and weight trump noise/drone/durability/price. The spec requires stock headers/HE but otherwise free after the flange. We're using dual Webers.

Also, are wheel studs available, hoping to get rid of the lug bolts. Bullet nose even better.

Thanks!

[Borderline]

Don't know about exhaust systems, but I just found this site the other day:

Track Studs

they have different length and quality of studs to choose from.

Good luck with your spec racer 914!

[campbellcj]

With carbs and a race application would you even want/need a muffler, versus megaphones?

[SirAndy]

With carbs and a race application would you even want/need a muffler, versus megaphones?

You need the back pressure, so *no* on the megaphones.

He said they need to keep the stock exchangers, which means the only place to do a crossover (to get the back-pressure) is in the muffler.

My choice would probably be a Triad muffler.
http://www.triadwestperformance.com/Products.htm


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[DanT]

my choice for that type of car would be either a Bursch or a partially gutted and twin piped stock banana muffler (IMG:style_emoticons/default/biggrin.gif)

[Brett W]

You need the back pressure, so *no* on the megaphones.

You don't need backpressure. That is synonymous with restriction. Needing backpressure for an engine to operate is the biggest myth floating around the interwebs right now. Engines do no function well with backpressure. Any amount of backpressure will hurt cylinder scavenging.

[SirAndy]

You need the back pressure, so *no* on the megaphones.

You don't need backpressure. That is synonymous with restriction. Needing backpressure for an engine to operate is the biggest myth floating around the interwebs right now. Engines do no function well with backpressure. Any amount of backpressure will hurt cylinder scavenging.

Interesting. (IMG:style_emoticons/default/idea.gif)

A well respected engine builder that frequents this board has said on numerous occasions that running an exhaust system without crossover on a T4 will net in loss of torque and HP.

His statements reflect my experience on the subject.
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[Brett W]

That still doesn't mean the engine needs backpressure to function properly. That means the engine is not properly tuned to use that type of exhaust.

[ChrisFoley]

You need the back pressure, so *no* on the megaphones.

You don't need backpressure. That is synonymous with restriction. Needing backpressure for an engine to operate is the biggest myth floating around the interwebs right now. Engines do no function well with backpressure. Any amount of backpressure will hurt cylinder scavenging.

Interesting. (IMG:style_emoticons/default/idea.gif)

A well respected engine builder that frequents this board has said on numerous occasions that running an exhaust system without crossover on a T4 will net in loss of torque and HP.

His statements reflect my experience on the subject.
(IMG:style_emoticons/default/popcorn[1].gif)

(IMG:style_emoticons/default/agree.gif) totally with Brett. Backpressure usually results in part of the exhaust charge being left in the combustion chamber, which dilutes the incoming air/fuel mixture.
I think the term used was "collector", not crossover, but even that is a gross oversimplification and isn't necessarily true.
Pipe length plays as important a role as anything in exhaust design.
The problem with most 914 aftermarket "headers" is that they add length to already too-long primaries.
The problem with megaphones on a 914-4 is that the bad cylinder pairing hurts torque/hp.

[Woody]

If this is the group that intends to run at Harris Hill Road then megaphones probably won't do. There are sound regs due to a pesky neighbor. I have an old Bursch that may fit and Consolidated, you are more than welcome to give it a try.

[consolidated]

If this is the group that intends to run at Harris Hill Road then megaphones probably won't do. There are sound regs due to a pesky neighbor. I have an old Bursch that may fit and Consolidated, you are more than welcome to give it a try.

Thanks Woody, I may take you up on the offer. My donor unfortunately is more rust than car so we're looking for another.

[Woody]

Have we met before? I'm the one running the silver 914 with the San Antonio PCA.

[consolidated]

I'm not sure, I'm in Austin so we've likely met at H2R. I'm usually in this car with PCA and NASA...hard to miss.

Please come check out the series next year, it should be a lot of fun.

[consolidated]

I decided to go with Triad, thanks all.

[EdwardBlume]

I'm not sure, I'm in Austin so we've likely met at H2R. I'm usually in this car with PCA and NASA...hard to miss.

Please come check out the series next year, it should be a lot of fun.

Cool BoxSpec.

I like what you did with the headlights especially... nice when you see a mod that is better than factory... (IMG:style_emoticons/default/cheer.gif)