NoRotors.com - RX7 Engine Swap Forum
Technical Information => Forced Induction/Nitrous => Topic started by: bigjoe25 on January 29, 2012, 02:57:28 PM
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1st thing you'll notice is I have ADD and go all over the place. Scatter brained, if you will. I do have serious questions about making more power though, on my budget.
Heh, really did have a dream last night where my car was twin turbo, but looked different. I'm an avid *cough legal* herb user, and tried wild lettuce for the 1st time. Such wacky dreams, felt it was real. Anyway, enough with the bull sharting, I do have a question reguarding compression ratios, octane, and forced induction.
So I know the things that affect compression are the cc of the head chambers, pistons, thickness of headgasket, yadda yadda. I was always under the impression if you had lower compression, i.e. 8.5, on say an old carbed 350, and if tunned correctly, then 87 octane isnt a problem, it's build for it.
Okay well, I have 86 rx7 with a simple sbc 350 swap, pretty sure the engine is also from an 86 vette, so that'd make it a pre 86 block. Wondering what they can hold? I think it would make it a 2 bolt main? Any way to tell?
Okay so I'm thinking of doing a low-compression, yet forged everything (cept for the 400 crank, those go for like 600hp right?) 8.3-9.5 compression, 383 stroker on the bottom end, maybe 64, 72cc heads?? Have no idea what port I'd use for this little project. I'd run a mild N/A cam, keep it carbed with the 670cc I got. Then get it nice and tuned to run on 87. My idea is to drive it around with the low comp, pretty much like a high torque, low rev truck engine in my mazda. Just a though then.....
I could get an efi intake, using megasquirt, already got a fuel cell so any fuel changes would be a snap, only run at leas 92 pctane, throw a different cam in her, Mod up the exhaust I have to put two small turbos, both of them maxing out before 8-9psi, each. Really small so boost comes at lower RPM. I know compression plays a role in spool up time too.......
Anyway the main question is that a feasible plan? Would the setup be too hard to achieve in stage one and stage two? Would putting turbo speced heads on the n/a cam and car mess it up too much to be tunable? Car drives fine as it sits atm, but I do hear a tappet noise on one of the heads. Sounds like some rocker arms need adjusted but could be a broken spring or something too. Hope the valve didn't tard smack the piston.
Anyone got any suggestions on how to do that? My buddy and I can rebuild the thing into an 383 soon as the machine shop can mod the block.
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I have kind of thought about the same thing. To run a small turbo on my carbed 350 but my engine wasn't originally built to be turbo and got fairly high compression. Thought about trying to run a blow thru set up with 5-7... MAYBE 10 psi. If I blow something, then just use what's left and replace the parts for some things that could actually handle it. If you decided to do that post some pics :) I would like to see how it is run.
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To answer your questions; Yes.
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To answer your questions; Yes.
IDK.. it could be a 4 bolt depending on the engine code...especially if its a vette engine.
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Isn't the difference in 2 bolt and 4 bolt = the amount of bolts that hold in the main bearings and crank? Taking the oil pan off and looking at those bolts would let you know if it's 2 bolt of 4 bolt. Mine unfortunately is only a 2 bolt lol.
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Isn't the difference in 2 bolt and 4 bolt = the amount of bolts that hold in the main bearings and crank? Taking the oil pan off and looking at those bolts would let you know if it's 2 bolt of 4 bolt. Mine unfortunately is only a 2 bolt lol.
Correct. Yeah, just get under there and take the oil pan off!
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If you're sure the motor is out of an 86 Vette then it's a 2-bolt main block.
L98's were all 2 bolt in 1986. That's when they introduced the 1 piece rear main seal. If you read the engine code on the front block pad you can reference it to make sure it was from an 86 Vette.
The best way to determine is to pull the pan. You will see 2 or 4 bolts at each
Can it be turbo'd? Short answer is yes. Do you want to turbo a 2-bolt main block? Probably not. Do you want to stroke a 2-bolt main block? Shouldn't be a problem.
That's what I have and it works great.
Here's a picture of a 4-bolt main block.
(http://i142.photobucket.com/albums/r104/Vettrock/100_0563.jpg)
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FWIW, if you're getting machine work for a stroker, you can have it converted to 4 bolt splayed caps, which are stronger than the stock 4 bolts anyway.
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FWIW, if you're getting machine work for a stroker, you can have it converted to 4 bolt splayed caps, which are stronger than the stock 4 bolts anyway.
Beat me to it, expensive but makes for a solid bottom end in the old SBC