compression decision
 

Hey guys im looking for a little bit of insight from those of you whom are a little more forged internal savvy than I. I am trying to figure out what will be my best route as far as a compression change for my block goes. I'm looking to finish my Z right at 800 whp so, I would like to pop the question of 9:1 or 10:1 I guess is as basic as I can ask it. I've been doing some forum crawling here(though now as I type this it never dawned on me to maybe check the 350z forums) and haven't seen anyone provide some real solid(per say) numbers as to when running 10:1 is no longer a good idea and bumping back to 9:1 is the best option. Also while I'm here if someone is good with compressor maps im looking to find out at what point my stage 2 GT2860RS w/ .86A/R will be maxed out psi wise on e85 at both 10:1 and 9:1(I would think in theory these compression differences would change those numbers as it will take more boost to produce equal power from the 9:1 stand point. correct me if I'm wrong though! I don't claim to know it all lol :tiphat:) thanks Z brothers! :bowdown:

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Paging Mr. Squeeze.

Yes squeeze. O&G. Sasha maybe? Chime in lol

Phunk might know the answer also, he has been doing 350z built motors for years and is on the verge with his 370z.

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Your very right dream plus he was offering a GB on 10:1 pistons so he might have decent insight on that

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I went with 10:1 cp pistons. 700-800 on pump gas is my ggoal. So I'm definitely interested. I went with carrillo rods so I believe I can hit some serious numbers on e85 with a good tune.

im going to stick to K1 rods/CP pistons personally. I wish I had 1700$ for those baller carrillo rods w/CARR fasteners(only way to go imo) but this build came well past unexpected for me so I didn't have as much time to start saving for it as I was trying too. im going to stop with 800. I couldn't imagine this car at 600; which scares me enough in its own just thinking about it; let alone 800. once I get all this figured out I will have some pretty interesting stuff to share with you guys! could be good info for anyone looking to go FI in the future(about my blown motor that is). I think my biggest limiting factor now will be my turbos.(maybe exhaust ill have to look and see the whp numbers that sasha posted up once that supra guys are running per exhaust diameter to find that answer) Im not quite sure how to go about upgrading those either really? can the compressor be upsized without changing the hot side? or will I have to talk to garrett about their core exchange program and just see about picking up two GT3071 w/ 86 A/R

Hold on, back that train up. Are you the first Fast Intentions casualty?

no sir did they have one already!? :(

Never mind. Carry on.

no sir im on the GTM stg 2 kit I was signed up for tonys' kit before I had to prioritize and budget a little bit. I will have one some day though if I don't decide big single is better for me

Twin Turbos

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theoretically yes. but squeeze and I are looking to push our cars for more straight line power and undoubtedly a big single is much better in that aspect than two small twins.

http://www.the370z.com/parts-sale-pr...0-shipped.html

Do it. Doooooooooooo ittttttttttttt.

I don't think we can fit 35 series turbos down there though can we chuck? maybe on the pass side but that driver side is tight as l-lell

No idea. For that price you could sell them if they don't fit and not be out any money.

I vote for 10:1 for VHR builds.

Greater efficiency in everything, better fuel mileage... drives nicer, more power out of fuel system and turbo system of choice...

Now I dont know if I would try to run 800rwhp with 10:1 on 93 octane. It could probably be done but I dont see the point in that.

But if you could deal with maybe 550-600 on pump, and 800 on E85, I see no reason to take away from the motor with lower compression. Possibly do a E98 tune for kill mode.

Who said anything about small?

Charles I bought your stage 2 system solely for the purpose of converting the car to E85 so, just as yourself the car will remain strictly a corn burning machine. if you feel that 800whp is attainable on e85 then I feel that all I need to figure out now is my path forward turbo wise. 550-600 daily tune 800 kill tune. those are my plans for the car now

So, the only way to make big numbers would be on e85? How far could we go safely on pump gas 93?

its not that its the "only" way there are tons of high hp cars on pump gas its more so a safety issue the way I understand it. why be skating by on pump gas when you could have cushion on more less race gas. as Charles stated I dunno how much over the 600 wheel area I would want to personally push on 93 octane

Not nearly as far as you can go safely on E85. I know on the ZR1's you can get an extra 100+ HP if you tune for E85 vs pump gas.

I have a customer that made 799rwhp with 93 octane in his G35. Its not that we cant make big 93 numbers. Its just that... expensive engine, difficult and time consuming to rebuild it. When running the engine at its highest power, I would take the precaution of more stable fuel.

I can tell you by looking at the compressor map of the GT2860RS turbos they will be out there efficiency range at 18-19 PSI after 7000 rpm's.This comes out to be 35 pounds of air a min at red line estimated 700 hp at the crank. You could probably get away with pushing them a little more but there is no point you would just be blowing hot air. There is really know way predict your power with E85 different compression ratios.

My advice to you if your keeping the GTM turbo kit I would upgrade the turbos. You can send them down to Forced Performance and upgrade your GT2860RS turbos to there HTA 2868 turbos for $700 each. This would make yours turbos similar to GTX 2867 and the compact GT3071 that I had in my kit.

The link is below.

Forced Performance Turbochargers: Turbo Upgrades

You are correct there are tons of high power cars on pump gas. Here is a graph of a GTR with a ETS turbo kit that using tubular manifold look at the 93 octane numbers. This is a very efficient turbo kit using GTX 3076R turbos. The trade of with a setup like this is more lag. The highest VQ I have ever seen or heard of was a 350z making a little more than 700whp.

http://i1311.photobucket.com/albums/...ps24c84fed.jpg




You can fit a 35 series turbo on our car using the T04b compact compressor housing same as the GT28 series turbos and GT3701 that GTM uses.

ohhh nice. Just a hour ago we got the motor for our 350z project back from the machine shop. We look forward to seeing what the GTX3076R's do on a VQ with our custom turbo kit... might end up having to put a pair on my 370 after the built motor goes in.

Info! I love info! Thank you squeeze! Only reason I questioned the turbo is that I would assume(once again speculation) that being that I'm running a higher octane fuel I could make more power per psi of boost so it could potentially bump the maximum hp output on the turbo up once again I only question this because in theory it makes sense. If I knew it all I wouldn't have to be here bothering you guys for answers :D. That HTA upgrade sounds like it could be the cats @ss vs spending 3k in new turbos I only question will it push 800 wheel? If not I may just ditch the TT kit and sign up for the BP kit and break even money wise if not overall better solely from the torque.

Why can someone not make a SS Mani for our cars like come on! My brothers mkiV has like 20 equal length manifold options and I get all jealous looking at his available manifold pron. I'm over here like yeahhhhh check out my bad@ss cast manifolds lol

because we are low volume low sales so no-one gives a **** about us. not to mention GOOD stainless manifolds that won't crack will cost around $1600 a set.

Not SS... but I hear these ones are really good..... VQ Turbo Manifolds

No different than surpas a good boost logic equal length mani will run you 1600 I would pay that for peace of mind knowing I won't end up with cracked sl-lit from a company that probably won't be around in the future to get replacements from.

Wow only 900 for brand new manis!?? Whoahoaaa!!

I think I'll place my money into better investments like that intake mani CJM may release one of these days ;) :tiphat:

I now have about 1000lbs of aluminum here to turn into DE and VHR rails... enough to last me a very very long time.... and 40 more twin pumps. Once I burn through that over the next few weeks... I will be good to go on nothing but new product development for the rest of the year. Finishing the intake manifold is a for sure thing.

That's what I like to hear man! Getting ish done for the community! That will definitely be one mod on my must have list. Squeeze you got any more info on the HTA upgrade? Only numbers I can find are from tony quoting them to be good to 1000 hp w/alpha cover found a few RB guys with them looking for the 750-800whp mark on twins but no one is really saying yes it's possible no its not. Dont want to wrap up 1400$ just to shoot myself in the foot.

Your best bet would prolly be talk to tturbo370. He has the same kit running e85 and built block. On e85 he made 800 I believe.

Right on el ill look and see if I can find him man! Thanks!

Can't wait for that manifold, I have a feeling someone is going to find out how weak this plastic manifold is very soon.