IM LOOKING FOR SOME INSIGHT.. Ok here’s the questions, which would you rather have and why also which makes more sense and why??.gen v LT platform only…

Would you rather have forged LT engine cam stock LT4 heads e85 etc.. with centrifugal/root either or dealing with 20lbs of boost with 10.5 compression ratio basically less likely KR ,more timing, bigger tuning window or

would you rather forged LT with Stock Lt1 heads 11.5 compression ,cam ,E85 and supporting mods.. centri/root 20lb of boost more prone to KR* upper rpm ,less timing , smaller timing window.. but better throttle response snappy, basically I’m guessing a little more efficient.. I could be wrong..

ok drag racing which setup is better suited?????

And another thing, can nitrous be added to both or 1 will be better? Forced Compressed nitrous verses low compression forced nitrous…

LETS HEAR SOME ANSWERS GUYS .. thanks

 

I've blown-up more severely boosted antique engines than the manufacturer ever imagined possible. Rule of thumb, the higher the boost the lower the compression. Actual amounts for appropriate balance depend on so many different variables it could and does fill books. What you need is a competent experienced builder/tuner of what you are wanting and listen to his advice. I've watched many ignore what they were told and have seen the results scattered all over the Salt Flats. Sorry, but I cannot be more specific with your individual build choices. All the best.

 

I'd rather have lower compression and more boost. Always. High boost and high compression leaves too much margin for error in tuning, fueling, altitude, weather, etc.

 

Drop the compression on FI. If not, drop in a new engine after you blow up the one with the high compression.

 

Yeah I understand years ago rule of thumb was more boost lower compression but seems like when you get down in debth with these LTs they are diff when talking compression just with how the direct injection is setup also with the ignition and diff cooling variables.for example I see E85 works better on one of these vs Ls engine basing it off number for number . But I Deff understand that lower compression and good bit of boost is rule of thumb the go to. I appreciate the honesty… YALL KEEP THE OPINIONS COMING!! Lol

 

My last FI was twin turbos on an LS6 block with hardened everything and a CR 9.0 I ran 17 PSI through it and got 735 at the rear wheels.

Sorry, that's all I got for you! THe real pros will give you more.

Elmer

 

As stated, there are tons of variables from how well you cool the intake charge to injection method to bore size to combustion chamber design to exhaust valve temps, to camshaft design and etc. Compression ratio is important for a lot of reasons. You obviously don't want too much, but too little is a problem, too. You can leave not only a lot of performance on the table, but it's also harder to tune and results in other problems if compression is too low.

You really shouldn't be building and hoping for the outcome you're happy with. You should have a goal, and then build to that goal. I want X hp. Then you work backwards to figure out how much boost you need and then figure out the compression ratio. That's obviously a 30k ft road map, but you figure out the designation, then map the roads, not map the roads and hope it's an acceptable destination.


Also, with regard to timing vs compression, you almost always want your timing optimized and compression dialed back. Pulling timing is a band aid, and not a good one. When you adjust timing, that means the fuel is burning too early and you're not optimizing the fuel/pressure. You already fire well before top dead center. The idea is you build up the pressure for the down (power) stroke. Make it happen early and you're building pressure to fight the piston from coming up (effectively, fighting the other cylinders making power) and not just "not making power" but also fighting your own HP.

 

Great info !! So tell me this.. dealing with 20lbs on boost on a f1 which route are you taking, Building around that unit?? Basic Goal is fast as can be with few options first mentioned in the scenario. Lt4 or lt1

 

You're still picking means rather than goals. 20lbs of boost and let's see how fast it will be, lol.

But as to your specific question, I've been out of it way too long to specify what parts to use. There are plenty of vendors that can probably answer your question. I always go through AMP myself.

 

I love compression and boost. Just can't be a ding dong with it and be a smart tuner, if you're that then it can go absolutely anywhere. My old combo was 11:1 on 31 psi and I cracked the stock sleeves after 10k miles of abuse. That's no one's fault other than eh **** happens.

 

I actually seen 1 of your responses on a post you mentioned you like compression and boost... yeah you were Deff was feeding that thing 😂😂

 

If you are going to run boost/forced induction then yes lower the compression if you are going to open the engine up and go thru it. AS several as said, lower the compression and up the boost and you will see better gains and wont be as limited due to cylinder pressures or cylinder temps.