PT-88 turbocharged 331 or 408?

[FiveOCapri79]

A buddy of mine is stating that I should go ahead and build a 408 for my turbo setup. My original plan is a 331. Both combos will be using a TKO-600 and aftermarket blocks. Help me decide! Also, what's the limit of a stock (let's say 1990) 351W block with a girdle and etc.?

 

[Rick 91GT]

A stock latemodel 351 block will break just like a stock 302, anything after 500HP gets hairy.

I prefer to build shorter stroke combos for a boosted motor, you do not want the 4" stroke or the long rod. If it were me I'd build a 3.25" stroke, 5.4" rod, 4.125" bore (Big bore 347ci, basically a 331 with a LARGE BORE) with the PT-88.

 

[FiveOCapri79]

Instead of the 408, how about something like a 393? On the big bore 347 you mentioned, is that the maximum bore the Dart block allows?

 

[Rick 91GT]

NO the DART or World Man-O-War block can go further then a 4.125" bore....

 

[srothfuss]

I think it's 4.2...? Rick will know for sure, but I think I remember reading that in my summit catalog.

 

[FiveOCapri79]

4.2 is quite a bore. Though I'd be afraid to push something that far since I'm trying to keep longetivity into the equation.

 

[blackcloud50]

I prefer to build shorter stroke combos for a boosted motor, you do not want the 4" stroke or the long rod.

Just curious, but could you give a little more insight as to why?

 

[stroked86]

I agree on the shorter stroke and larger bore for a blower motor but I would rather use a bigger stroke same size rod and a smaller bore on a turbo..... the extra stroke really helps the turbo work!

The dart blocks can go out to 4.200 But I wouldnt suggest it.... no matter what it can go out to the walls will still get thin becuase the bore spacing is still the same as a standard block... the most I would go is in the 4.150 range but try to stay around 4.125

 

[304billet]

I would do a Dart IE 408 stroker w/ Scat profiled 4340 forged steel crank, Scat 4340 H-beams w/ ARP 2000 rod bolt upgrade, Ross, CP, BME, Probe flat top pistons 9:1 comp, neutral balanced, rotating assembly good to 1000hp, block to to 2000hp. Over 1000hp go to billet steel crank and rods.

AFR 225, TFS Hi-Port Stage 3 heads, TFS R Stage 3 heads, Super victor intake converted to EFI, TFS R intake port matched, custom cam, Jesel shaft rockers.

Bennetracing.com has these 408W crate motors dyno tested at 575fwhp, 540fwtq, NA, 10.3:1 comp on pump gas daily driver. throw the turbo on there turn up the boost and ur close to 1000fwhp.

A good 331 stroker can put down 460/460 @ the flywheel NA on pump gas w/10:1 comp. u can see the difference in power output. It really depends on what u after.

I would also do a TKO 750 or 900 from modularmustangracing.com. They take a TKO 600 and deburr and cryo the gears. cost $1900/2100. good to 750 or 900fwtq. The owner of this shop was the first guy to go 8.99 and 154mph in a 5 speed Tremec, had a twin turbo on it.

An early model 1969W block can hold 900-1000fwhp. Still with ur power level this won't be strong enough and I would not even chance it. These blocks r good for NA motors but I would be weary doing a turbo. my friend is a 65 year old engine builder who has a 408 W that put down 650rwhp w/ 12lbs of boost. He stroked it to a 418W and now is going to nitrous, sonic checked that 69 block and it was fine. I don't like living on the edge. I went to a SVO R302 block and billet steel rotating assembly and never have to worry about it splitting or a crank/rod giving way.

 

[FiveOCapri79]

I wasn't aware of a TKO 750 or 900. I'll keep that in mind. On compression for any motor I decide, I was still wanting a low compression piston since I'd like to be able to turn up the boost safely and still run on 93 pump gas. Streetability is the key factor in my build so I'm not trying to go too wild with it. Time wise, I'd say my goal is around 9.5 or so with a very conservative tune. Say I was to get an early model 351W block, used the valley girdle, Milodon 4 bolt main caps, and main girdled. Think it'd hold up then?

 

[304billet]

The only way u can get a TKO 750 or 900 is thru MMR.

9 or 9.5 comp the choice is urs. I like 9:1. My friend's R317ci stroker w/ 25lbs of boost from a YSi trim and 9:1 comp puts down 740rwhp thru a TKO ll. Another friend has a 347 stroker w/9.75:1 puts down 500rwhp and has been as high as 611/630 rw on a stock 302 block and C114 race gas but it scared the hell out of him because at any moment that block might split. My engine builders drag car is a 92 notch R331 stroker w/ 11:1 comp and he is pushing thru 25lbs from a YSi and puts down 780rwhp.

The 69W block would work but valley girdles r worthless. And main girdles will not add block strength, they only hold and protect the rotating assembly together when the block splits. It's the valley that splits and splaying the main caps does not help that. My friend who built that 418W has done this all his life and if he says the 69W block can hold 1000fwhp then I believe him. He says the 69W blocks were cast in Mexico with the early model 302 blocks.

I would not take it over 800rwhp with the 69W block though.

 

[blackcloud50]

I agree on the shorter stroke and larger bore for a blower motor

Can you give a little info or reasoning behind this statement? Thanks

 

[88Stang331]

I would say 331 with 9:1 compression that way your low end is still there and it leaves room to boost.