Just like the title states.....'04 Road Glide S&S 106 Stroker 10.5:1 to much for a Trask Turbo setup?

 

Not so much the mechanical number but the concern is the ccp.
About 175 -180 psi seems to work well, or at least from what we've seen.
Scott

 

Sounds good thanks for the info Scott.

 

You bet.
Scott

 

Your better off running a lower compression ratio and using more boost. You should get better returns in performance going this route.

 

Okay, I'll try a serious answer.

In my opinion, yes it's too high! Having said that it all depends upon how tight/well your engine is built, what fuel you run and ignition setup, inter cooler used or not...(among other things, but I think these are the main factors). Search online for boost compression calculators and plug your numbers in....I think RB Racing have a good one on their site. What you will find is that the actual compression under boost can get really high!

For example... My stock compression Evo starts at 8.5:1 compression, however under full boost the real compression in the motor goes well above 15:1! I used to think this would be a problem, but experience shows that the right fuel and ignition curve means I do not have any pinging problems so I guess I'm lucky. I have had the boost up to 20lbs (not deliberate though - my waste gate system locked shut).

Typical I run around 8lbs of boost through a CV40 carb and no intercooler. I run her rich, particularly at full boost (perhaps too rich at times, but better safe than sorry), plus it's a carb, so tuning options get a little tricky under boost as opposed to an EFI setup.

At the end of the day you can run whatever compression your motor can handle. The main thing to look out for is pre-ignition or pinging, which will wreak your motor quicker than hell when your running under boost.

Also look out for cylinder blow by which gets worse the higher the internal compression is....you may need an oil catch can (pretty standard on blown motors)

I would chat to the chaps at Trask and see what their recommendation is...plus what cam they recommend as while you can run a hot cam your best to go with something designed for a blower engine (in my case it's an Andrews EV31 turbo cam, although I have had great success with an EV35 as well - but that one was very peaky)

Cheers

PS: whatever you do.... You HAVE to install the turbo! Nothing beats the experience of a blower Harley!

 

I have 10.5 compression on my 120R/Trask. Trask now offers a cam setup for their units but I can't get the specs for the cams and won't spend money without specs.

 

More compression equals less boost which equals less power.Ideally you want to be around 9.5-1 .When you start running too high compression you have to start dealing with detination.When these motors start cranking up a lot of **** can go wrong in a very short order if there not set -up correctly.

 

Here is the link I had in mind. I use it when setting up the boost levels on my Evo.

https://www.rbracing-rsr.com/compression.htm

A Trask set-up on a 10.5:1 static running 5lbs of boost only hits 14.7:1 compression ratio so that's fine IMO. My theory is that you can go up to around 15:1 without having to do special 'stuff' to the engine like 'o' ring the heads etc.

Also, if Trask offer blower cams then just use those or check out Drago works as I think he does a good cam as well.

 

Thanks for all the info fellas.....decisions, decisions.

The 106 is definitly a hot rod, w/ Baisley Heads, RB pipe, Hopped ip ration roller rockers, S&S crank w/ dark horse reinforcements.....list goes on. Lately we started spraying it and gain are awesome, but as usual more is wanted!

I'm thinking there would be more safer/bigger gain if I started out w/ a lower compression, but will need to further research.

Definitely will check out the RB calculator.