I am wondering if 10.4:1 CR with a superchager is a good combo. Will detonation be a problem? What would be the Max boost pressure and spark I could run. What octane gasoline will I need to use. I will also be running an air to water aftercooler.
10.4:1 CR with a V1 S-Trim Anybody running this?
- Thread starter Cobra52898
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10.4 to 1 is pretty high for forced induction. You need to run the highest octane gas available to you, and I would only go centrifugal if I were you. If you have and IC you should be able to run a fair amount of boost, for example im running 14-15 psi on 9.8-1 CR with an intercooler my idle air temps are only slightly above ambient temperature even on a hot day. provided your motor is forged ( if not thats a pretty odd CR) and you get a nice laid back tune I dont think you will have any detonation, SHM claimed to be using 10-1+ cr in all of their centri engines. If you are going roots or TS thats a horrible build idea.
While I won't support or dismiss your idea, I will state this.
Look at dynamic CR's based upon static CR and boost. You will see that a high boost, low CR car will have a similar dynamic CR to a low boost, high CR car.
Look at dynamic CR's based upon static CR and boost. You will see that a high boost, low CR car will have a similar dynamic CR to a low boost, high CR car.
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Where you live you have 93 octane.. I would run no more than 10psi on 93 and you should be ok.
I definitely wouldn't go lower... You could easily go higher if you wanted to as well, just get a nice tune on the car. A high compression motor will make more pre-boost numbers(important on a centri/turbo car) and you won't have to spin your blower as hard, which means less wear& tear and less heat.
in a perfect world id go for your theoretical setup. flat tops + boost + e85.
as i mentioned before i was literally in the same exact boat. i went with lower compression. its just plain not worth the risk for an extra 3mph in trap speed or whatever. but as long as your confident in your abilities and equipment..
as i mentioned before i was literally in the same exact boat. i went with lower compression. its just plain not worth the risk for an extra 3mph in trap speed or whatever. but as long as your confident in your abilities and equipment..
This is true. The added benefit of a higher CR is faster spool up (centri or turbo). Also, a higher CR engine will have better throttle response and is just plain more efficient. The 2011's are 11:1 and they run relatively low boost and are ok. I went with 10:1 on my turbo set-up and should have gone with flat tops.
Do it. You'll also make a ton of tq for a centri blown car too if u go with higher compression. Im.running a v2 s-trim with 11:1 cr, but I use e85. You could probably get by with 93 oct if u keep boost around 10psi and use meth. That should still get u 500rwhp+ and around 500tq.
yeah you should be fine as long as you keep the boost at a manageable level and use the proper fuel, plus a good tune, i think you can also just build up the motor NA as much as you could afford to at least, then throw the blower on and get the tune done, I'm positive if you do the build right 10:1 shouldn't give you any issues, hell i know it's a German car but there are Porsche guys turboing 12.3;1 compression engines, they also have crap loads more cash but still
im doing a 10.4:1 comp 03 cobra motor with my whipple 3.4 crusher at 25 lbs of boost, yes i will have to run c-16 in it but when you put stage 3 cams in with a low comp motor it becomes lazy esp if you degree the cams in where comp wants them set at
Thanks for all the feedback, I really appreciate it.
I've run 10.3:1 compression with an F2M procharger at 16-18psi on 93 octane with no issues at all. I've pushed 24psi on the same setup with E85. I had custom cams in that setup that kept the dynamic compression in check though, so keep in mind there is more to it then just the pistons etc.
Will meth injection be necessary with an aftercooler on 93 octane?
I planned to keep the stock 98 cams at least for the time being.
My next motor will be 10:1 with boost.....I've done lots of research that's the way to go on a centri build. Just use e85 or meth.
exactly.. these aren't old school 350's with 871's on them.. I like mid 9's to low 10's CR and boost..
Drop the compression too low and you have a lazy powerband that's completely dependent on your power adder..
My 408 is looking like it's going to be 9.8:1 with 10-12# on 91
That is exactly what I am afraid of and want to avoid.
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