limiting factors

[jdmser]

What else besides the cast pistons limit the rb20 from making big power. I've seen plenty of small displacement turbo motors make good power, why can't the rb20? What's the highest horsepower rb20 out there right now? I've looked around the intraweb for anwsers to these questions for a while now and was hoping someone could shed of light. h
Modified by jdmser at 1:55 AM 11/19/2007

[jdmser]

Is this to say that nobody has ever thought of making big horse power with the "out of date" rb20. Yeah, I know there are easier ways to do it but, give be a break I just finished watch Worlds Fastest Indian and looking at a buddy's 950hp dyno sheet.

[Carl H]

check out the skylines austraila dyno thread, there are guys making 500hp on a std 20 block now...pretty insane.

[Yellow4g63]

Limiting factor is the head. If a master works it over and gets it to flow more you can make way more hp lol. Head makes the power and the bottom end holds the power.

[Carl H]

and in reality all you need is a good set of cams to get the head to flow...my old dyno sheets are proof.

[jdmser]

Are the 260s big enough? I've got the port and polish, should I start looking into bigger valves? I plan on doing the piston end of next season. What about the turbo, I did put the numbers in the map for a t3/to4e but, doesn't the trim and a/r change the map so you can't use one map for all t3/to4es?

[DriftingisLame]

I've got my rb20 apart right now. I've always read how poorly the stock head flows, on the aussie forums and such. Although, I really cant find any major flaws with the factory head, I admit, the valves look very slightly too small, but how large of valves do you need to release 333cc's of exhaust? I'm convinced there are only 2 problematic area's of the factory rb20 cylinder head.

Camshafts: Would increase the efficiency of the (maybe) small valves. Considerably higher lift (9mm+), and whatever duration you prefer, to determine the idle you're after (or lack thereof!) Seriously, stock cams work well for a stock motor. 7.5mm lift? 240 duration? Thats weak sauce. On another note, "Forced Induction performance tuning" By Grahm Bell, claims I believe a 18 hp gain with *no* loss in torque from a properly adjusted set of Cam gears. Pretty much every rpm past 4500 I believe gained a considerable amount of power. I'll write up the article if more people are interested in this (they do 3 dyno pulls with 3 different setups on the RB20). Seriously, buy the book, its amazing. I suggest reading "Four stroke performance tuning" first.

Lifters: The only other thing I'd worry about in the head is getting cams with a lift that would overwork the factory hydro lifters. I personally dont think its worth the effort, and valve adjustments, to upgrade lifters, but I'm not going for world record horsepower, and will never get a set of cams that recommend solid lifters, in favor of simplicity.

After that, if your still wanting more power, and choose to do so by way of increasing the RPM, valve springs may be in order, but I cant say that from experience.

Any comments?

[drifter92sx]

yea tru but on most turb. motor if you wanna make good power you have to build the head first the head is everything

[Darius]

The bottom end is basically a pump and the head is where all the power is pulled from. Like everyone above has said, cams, and head work make all the difference in power.

[Coolwhip]

a focus on the way the air goes in and out of the motors are key as well. Manifold design on both intake and exhaust aids this process as well.

[240z4u]

Cash, most people stop dumping money into motors at the point of diminishing returns. Just being realistic.

I agree with above though.

Evan

[jdmser]

Holy back from the dead! When I first started this thread over a year ago I was thinking about doing a set of forged piston. Now I'm about half way done with the RB24 short block. There is no doubt in my mind that there are cheaper ways to make horse power but, if I was just in it for cheap power I would have went with a LS1.

[nissandrftr88]

bump for a dead thread i googled...

Any dyno numbers on your RB24??I'm prob gonna build one.Did you use a 26 crank ,26 rods and cp pistons for a 4agze?

I came across this thread looking for the highest hp rb20.

as i would like to know where i stand right now.

[jdmser]

Back ordered parts have the project on hold right now. I'm waiting on a gasket set and an exhaust valve. I recently dropped the intake off for a friend to weld, the short block has been filled and assembled, and I cleaned up the engine bay while I wait. We're shooting for next spring. The short block is made up of custom 82mm coated JE pistons, ACL coated race bearings, R33 RB26 crank, and RB26 Eagle rods.
Modified by jdmser at 1:58 AM 8/31/2009