what waste gate should I use?
 

I need to get a waste gate and BOV, and I need to know what to purchase.

Stock, Tial what is suitable?

This is what I have to work with

3.6 8:1 CR
GSF 1.625 headers - until I have the coin for Rarly8 headers
K27 with k29 hot side run at 1 Bar

Tial 46mm but others have bought some off eBay for less. TheTial is a great product with support.

If you wish originality, by all means go with the factory unit. Just be aware these units are getting long on the tooth and getting replacement parts are increasing difficult to get and EXPENSIVE.
I agree with A930Rocket, the Tial's are fantastic units and have a 46mm unit on my car. It is a very good unit with a vast array of springs to tune your boost threshold. Much easier to replace/modify spring(s) than the factory unit, IMHO.

If you have a factory wastegate and there is nothing wrong with it there is no reason or advantage to changing. Unless you just like to spend money.

The bov choices are many. There is a nice " quicker turbo Response " advantage
when using a 965 style bov setup.

Cole

I've tried a few and keep coming back to TiAL simply due to quality. This one little bolt-on part can destroy your engine in a heartbeat should it fail to open.
With 8:1 C/R I would think 1.0bar too much boost. If so the stock WG can be left in place as-is.

is there a model I should buy?

Brian, boost level at 8:1 would be .8? I hav'nt purchased the pistons yet, what CR would be suitable for a 3.6?

some one was telling me that I can machine the stock pistons in the 3.6 is this advisable?

Also a friend has donated a turbo a k27 witha K29 (hence my othe thread) hot side he had it on his race car and hes said it kicked in at 2200 and ran out of puff in the mid 5's but pulls hard in the lower and mid range, as my application is for the street I'm thinking I could use this and save some $$ until i get bored and want more boost.

I'd get bored real fast if my turbo ran out of steam in the mid 5's....

Question
 

This is for Rarlyl8.

Rarlyl8,

Rather than starting a whole new thread I thought I could ask you a question on this thread.

If I have a stock WUR (and stock everything else) and I go pig rich (10.1 or 9.9) at WOT why couldn't I use a 1.0 bar boost spring? Will I still have a chance at detonation if I am within my AFR limit? Or is there another factor at play here that could hurt me? Is all I have is SC cams otherwise the motor is stock and rebuilt on an 87-930

Thanks,
Bryan

Bro, I would say that you would never want to use the 1.0 bar spring with the stock turbo nor with the stock I/C. First off the stock turbo will run out of steam, so if you ask it to increase the boost pressure, it also increases the temp of the air as well. Then throw in the sotck I/C, which is about worthless, and you have very hot air that is going to your cylinders. I really dont think this has much to do if you are pig rich or not at this point. Even though at high boost levels with CIS, it wouldnt hurt....

to the OP... I would say go TiAL all the way. I have rebuild several stock WG's over the years. I will tell you one thing... they are heavy!!! Think of all that weight that is just hanging on to your headers. I have dual TiAl 38mm on my new set of headers and let me tell you... AWESOME quality. They are small, lightweight, and man they look great. Since it is harder to source parts for the OEM WG, If I was needing to replace the stock WG, I would not bat an eye... Go with TiAL......

+1

I would go further to say its a waste of time and money to even try mounting that thing on a 3.6L.

Bryan - you can go to 10:1 AFR and have detonation (there are other factors to detonation). You need to tune that motor a bit rather than trying to put the fire out with all that gas. No doubt, it helps to have lots of fuel, but timing, proper plugs, ignition system, type of fuel, air inlet temps, compression ratio and so on contribute. Personally, I would keep the stock spring until I got it all sorted out.

Bryan, I think you may be confusing AFR and octane rating. As Don states you can't put the fire out by drowning with gasoline, unless it is the right formula of gasoline. Many factors go into the source and treshold of detonation and octane is but one method to increase that threshold. Our 2 valve air cooled engines are a long way from optimal when it comes to controlling the combustion environment.

Matt, the stock boost level on a 7.0:1 930 engine was ~0.75bar. I wouldn't go above that with 8:1 given all other things equal. You need a margin of safety for all the varied operating conditions your engine will see (as in the above paragraph). Higher octane fuel, large intercoolers, etc will put off detonation of course and allow you to safely run more boost.
Matching a turbo to a high compression high reving engine is a challenge. You need a turbo that will boost well below 0.8bar at 6000rpm while flowing the required air for your displacement. Marty (Copbait73) is a turbo expert and can help you with this.

Thanks
 

Brad, Don and Brian. Thanks for the help. I am mostly stock and probably will stay that way.

Bryan