I'm building a new motor for the autocross car this winter and the class I run in only allows stock rebuilds. 1st overbore, head and block shaved to factory spec. I also run header and CAI. Most of the cars in the class are the same as my CRX Si so competition is very close and I'm looking for every advantage I can get.

My question is about rod and main bearings. Is there any advantage to building a motor with slightly bigger clearances around the bearings? Will this free up any power? I'm basically thinking about going one size thinner on all the bearings if there is an advantage. The car is nationally competitive so I'm at the point where I'm looking for tenths of a second and every little bit counts. How much longevity will I be giving up if I go with the bigger clearances? TIA, I look forward to the advice.

 

yes you can run them loose and also run narrower bearings.

 

I was planning to run Honda bearings, what brand of bearings would you use to go narrower? Thanks again!

 

Actually there are different oem bearings that are.. Take a look at the ls,b16 and gsr rod bearings and you will see the difference.

 

You want to run the 90-91 si cam in your hatch, because its more aggressive then the 89 cam. I'm trying to remember all the little power adders that can help. We were going to rebuild my bosses motor last year>chris shenefield, but we decided not to. Their are lots of little things you can do but most people won't tell you.

 

We built a similar motor for ben bricker(uncle ben) here on h-t for his scca ita car.

loose bearing clearances, tight piston to wall, and a nice little combustion chamber.

expect anywhere from 125-130whp out of these little a6s.

also a good header really makes a difference on these engine...smsp

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by goforbroke &raquo;</TD></TR><TR><TD CLASS="quote">You want to run the 90-91 si cam in your hatch, because its more aggressive then the 89 cam. I'm trying to remember all the little power adders that can help. We were going to rebuild my bosses motor last year&gt;chris shenefield, but we decided not to. Their are lots of little things you can do but most people won't tell you.</TD></TR></TABLE>

Is there a difference between the 89 and 90-91 cam? I thought it was just the 88 CRX Si that had the cam that wasn't as good.

So you work for RedShift? I met Chris a few years ago when I ran STS against him Nationally (&lt;--- read got my butt kicked by him). Great guy, he gave me a good deal on the OBX header I'm still running.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by WAFFLES &raquo;</TD></TR><TR><TD CLASS="quote">We built a similar motor for ben bricker(uncle ben) here on h-t for his scca ita car.

loose bearing clearances, tight piston to wall, and a nice little combustion chamber.

expect anywhere from 125-130whp out of these little a6s.

also a good header really makes a difference on these engine...smsp</TD></TR></TABLE>

I can't mess with the combustion chamber but I plan to "optimize" eveything else I can. How loose can you go on the bearings? How close on the piston to wall clearances? A better header is on the list, I've already been in touch with SMSP and got an idea of how much I'm looking at. Now I'm debating which will give me more gains, replacing the OBX header with an SMSP or picking up 2 SSR Type C's 15x7.5's for the front of the CRX to replace the 15x7 Enkei RPF-1's. God I wish I had a bigger race budget sometimes

Thanks again for the advice!

 

Only 1 color size diff.? Call Jim Justice in MD.

 

I am curious on this subject as I have heard this many times before. I have heard a loose motor makes more power.