Billet Main \ Girdle Questions

[shumpertdavid]

I'm putting together a .020 over N\A 231. The block is and 84 non turbo, I'm using turbo crank, 2 dot rods, arp main studs, arp head bolts, arp rod bolts, roller cam, ported iron heads, ross pistons (10:1). I'm going to spray 250hp Nitrous.

My question is do I need billet mains and if so just # 2 and 3 or all of them, or would a girdle work. I want this motor to hold up and be dependable. Please help me out. thanks, david

 

[SMS]

If this engine is going to N/A, I don't think you will ever make enough power to need billet caps or a girdle, unless you were to spray it with a boatload of nitrous.

There are turbo cars here that have touched the high 10 sec range with a completely stock bottom end, although it's risky!

Ok. I guess I should have read ALL your post. I still think the engine can live with a stock bottom.

 

[shumpertdavid]

define boatload of nitrous, I'm estimating motor and nitrous hp to be 500-550 range

 

[SMS]

I believe the general consensus is 500 hp is about the limit with a stock block. When the billet caps are used, usually just the center 2 are installed even though they make replacements for all of them. I also think even with billet caps or a girdle, using a stock cast crank will then become the weak point.

 

[shumpertdavid]

I was thinking that the stock turbo crank was good for about 500 hp and the stock rod's with arp hardware about 700 hp. I just didn't know if the caps would be recommended

 

[TurboCrazy]

The center steel caps are much easier to do. And with a steel crank, good to 600 hp or maybe a little more. For your application I think a girdle would be worth the money, if you want reliability. Nitrous can really pound a bottom end, even with a good tune-up. My .02:biggrin:

 

[paintitblack]

The center steel caps are much easier to do. And with a steel crank, good to 600 hp or maybe a little more. For your application I think a girdle would be worth the money, if you want reliability. Nitrous can really pound a bottom end, even with a good tune-up. My .02:biggrin:

+1

 

[turbofabricator]

Steel caps are VERY difficult to install. Aside from machining the caps flat, a girdle is alot easier. AND stronger. Only a line hone is needed. Steel caps requireline bore, line hone AFTER machining the registers, ovaling the holes (if needed) and fitting the caps. Long process to be done correctly. A girdle will strengthen the block ALOT! 10:1 with 250 nitrous is a bit on the low side for most nitrous applications. It'll work, but if you are building a race engine, then look to 13:1+

 

[shumpertdavid]

it's a street car that I've been working on for a long time. getting around to putting together my second motor for it and I don't risk damaging my investment. I figure for a street car with what I estimate to be around 250 hp then spraying another 250 will be pretty good

 

[street6]

I agree with the girdle being easier. the main caps requires alot of machining. And girdle will be stronger.

 

[HP Man]

My advice and other big name TR Engine builders is to run a forged crank with all billet caps. Crank flexing is what really destroys the bottom end with the cast crank. Whatever machining is necessary makes the bottom end survive. Make sure the caps are 90* to the crank centerline. I would also cryrogentically treat the complete block. My .02$ and Other's. HTH Gene

 

[GNBRETT]

I would also cryrogentically treat the complete block

I wasn't aware that was even possible. Who would perform that?

 

[charlief1]

Do a search on google for cryo treatment. People have been doing it for over 15 years now Brett. Works to improve accuracy of rifles as well.

 

[GNBRETT]

Ok, thanx...

 

[HP Man]

I own a "Benelli" Shot Gun that the barrel is treated. A local company does it, $150. This aligns all the metal pores and adds strength. NASCAR Engine Builders do this to all their engine block and maybe other parts? To me this is the icing on the cake to make an engine survive. Gene

 

[SMS]

As long as we are finished with the original question, is it even possible to double the HP of an engine with nitrous? I have seen 800 hp engines sprayed with a 300 shot, but never a 250 hp engine with another 250 shot of nitrous. Is it possible to move that much fuel and nitrous/air through an engine?

 

[Blazer406]

The '84 block is weaker than the '86 - '87 best I can tell from reading here.... so keep that in mind.

I agree above.... girdle would be best....

adding 250HP with nitrous.... IMHO... is harder on a block/rods/crank than adding 250HP with a turbo..... the turbo doesn't "shock load" the system like NOS does......

Someone else might disagree....

 

[yullose]

You know what would be cool ? AND make more power than nitrous ?

A blow-thru setup.

Use a set of factory 86/87 headers, mount a turbo on it and blow thru the carb. :wink:

Not to mention... it will be WAY easier on parts.

Hell... you could even use a front mount intercooler and piping... all you'd need is a CSU prepped blow-thru carb and carb hat.

No chips, cam sensors or injectors to hassle with... drop in a distributor, set timing and put fuel to the carb... BAM you are ready to go.