Building a bottom end for FI ?

sparq · #1 03-25-2002, 11:23 AM

Got a question about building a bottom end to go forced induction. Now, what compression ratio is BAD to have on your motor before going FI? Just as an example... I was looking at a B20 swap and it said the compression was like 11:1 (CRV-TEC w/ B16 head and flat top piston) -- so if I went with like the Endyn pistons that are 9.58-10.02:1 would it be worth it as far as power gains if I went with a supercharger -- because arent superchargers designed to run on stock internals anyways? Would I get slightly better fuel economy with the lower compression?

Im not saying im doing that -- but I was just wondering if it were at all possible, and advanced timing... ive been looking at some of these swaps and CRV-TEC says with stock valves on the B16 head that at 4 degree advanced timing they actually touch the top of the piston, but normal timing and even 2 degree timing is ok -- would there be any gain from 2 degree advanced timing? Again, just looking to expand my knowledge -- thanks guys!

90CRXZCSi · #2 03-25-2002, 12:07 PM

I understand that you werent gonna do the CRVTEC swap but it's a bad idea to do. The compression is too high. If you were wanting to boost any motor then i would go with the LS(either B18A or B18B) because the compression is 9.2:1 and is almost like just perfect for boost. I had a friend named Richie who had a 91 Integra RS boosted at 16 PSi and i think it was just perfect. At the time i didnt like hondas but once i rode in this...i fell in love with them. So that was my long story just to tell you about the LS/GS/RS motor being boosted.

mellowboy · #3 03-25-2002, 12:27 PM

Quote:

Originally posted by 90CRXZCSi
I understand that you werent gonna do the CRVTEC swap but it's a bad idea to do. The compression is too high. If you were wanting to boost any motor then i would go with the LS(either B18A or B18B) because the compression is 9.2:1 and is almost like just perfect for boost. I had a friend named Richie who had a 91 Integra RS boosted at 16 PSi and i think it was just perfect. At the time i didnt like hondas but once i rode in this...i fell in love with them. So that was my long story just to tell you about the LS/GS/RS motor being boosted.

I disagree on that. U don't have to have low compression or a built bottom end to run Force induction. U can go force induction with high compression but lower boost. You can still be as fast as the built bottom end and it cost less also. Theres guys out there running like 10-12 seconds with low boost (12-18 psi) on a stock bottom end. ITs all about tuning and a/f . You can use it as a daily driver also.

sparq · #4 03-26-2002, 02:20 PM

Like I said, im not trying to do this -- just looking for info. And I already mentioned I could get low compression pistons (9.58:1) to help with the forced induction -- that isnt much higher then your friends 9.2 so I dont know why you would say that you cant FI it without problems... now if I was talking about strapping a turbo onto a B18c5 without any compression drops, then hell yes problem city... I just do not see where you get the justification to say that it will be problematic...

If for example it was supercharged w/ upgraded pulley kit for 8 psi -- would I have a problem with all stock parts? And if I would be fine, what would I gain by using a lower compression piston?

kane2g · #5 03-26-2002, 08:55 PM

You guys are confusing 2 ways to FI.
What you loose in CR you make up w/ boost. So for superchargers if you would do only 8psi, i would recomend gettin it tuned right and stay with stock pistons (unless you want to make bottom end bulletproof)
If you went Turbo way, you have a lot more PSI that you got to deal with, so it would be better to lower the compression by getting the 9.xx pistons. but w/ turbo you can run as much PSI as you want untill you start to detonate.

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