Need advise on Short Blocks

[91StangLX]

Looks like I will be in the market for a new short block real soon. I was thinking of a FRPP 302 sportsman block or maybe a mild stroker of 306-308 or 327-331. Would like some recommendations on short blocks the forum members have had experience with and what type of horsepower and reliability the short blocks produce. Also any type of problems if any while installing the short blocks into their stangs. I would like to stay in the 325-350 hp range... I plan on staying naturally asperated and I would not be adding any power adders. I want to stay with the EFI setup.

Thanks

 

[Michael Yount]

If you're gonna stay in the 325-350HP range, a stock short block will be up to the task; the FRPP block should be fine also. Sticking with efi, that HP range and hydraulic rollers, I'm assuming you won't be spinning it much past 6000 rpm - the stock or Sportsman blocks should be fine for that too. You should be able to pull yours and use it as the basis for the new motor if you like - then you'll know for sure that everything will go back together and in just as it came out. If you go with a stroker, be sure to have a competent machine shop help you with any dimensioning/clearancing work that needs to be done.

 

[Rick 91GT]

A 306 is a 302 with a .030 bore..no stroker
A 308 is a 302 with a .040 bore..no stroker

A 327 is a 3.25" stroker crank, 5.4" rod, 1.165 CH piston with a stock bore, .030 gives you a 331
A 342 is a 3.40" stroker crank, 5.4" rod, 1.10 CH piston with a stock bore, .030 gives you a 347

You mention the Ford Sportsman block, this is a beefier block that should take 600hp with no issue. I am not sure if they sell that in a shortblock form with internals.

A nice cast 331 or 347 stroker kit will outlive a stock production block and will get you to your goal with no issues at all with the right supporting components. Why not buy a kit for around $1000 and then have a local machine shop use a stock block or a Sportsman block for the buildup, machine cost will be around $500 total, including balancing, align honing, boring, decking, etc...

I'm building up a 331 right now for a friend, Scat 9000 series crank, Probe I beams, Probe SRS series pistons, Total Seal rings, Clevitte bearings, AFR 185's, cam is undecided, Typhoon intake, 70mm TB, 75mm MAF, heades, full exhaust etc and it should have no problem making the numbers you are after, even through the AOD.

 

[Michael Yount]

Rick - I had the same reaction as you on displacements, but when I re-read his post, I think he's aware of what combines to produce different displacements. I think he meant an FRPP Sportsman based 306 or 308; or a stroker of 327-331. And, if I'm not mistaken - .040" over is a 308 (307.7). .060" over is 311 (310.7). However, on stock blocks it's strongly recommended that cylinder wall thickness be checked before going .060" over due to core shift and the fact that some cylinders may not have enough wall thickness to safely handle that much overbore. I believe any first-rate engine machine shop will want to check wall thickness on any overbore - even .030".

 

[Rick 91GT]

Rick - I had the same reaction as you on displacements, but when I re-read his post, I think he's aware of what combines to produce different displacements. I think he meant an FRPP Sportsman based 306 or 308; or a stroker of 327-331. And, if I'm not mistaken - .040" over is a 308 (307.7). .060" over is 311 (310.7). However, on stock blocks it's strongly recommended that cylinder wall thickness be checked before going .060" over due to core shift and the fact that some cylinders may not have enough wall thickness to safely handle that much overbore. I believe any first-rate engine machine shop will want to check wall thickness on any overbore - even .030".

My fingers were too quick for my brain, yes .040 is a 308.... Very true on the cylinder thickness, most will take .030 over with no issue. After that it needs to be sonic checked, as the late model blocks are not the best, and most builders/shops check the blocks anyways..better to be safe then sorry.

I noticed he already has a .030 motor so re-using his block is most likely out of the question.

 

[91StangLX]

My fingers were too quick for my brain, yes .040 is a 308.... Very true on the cylinder thickness, most will take .030 over with no issue. After that it needs to be sonic checked, as the late model blocks are not the best, and most builders/shops check the blocks anyways..better to be safe then sorry.

I noticed he already has a .030 motor so re-using his block is most likely out of the question.

Yes I was aware of what it takes to get the different displacements. I could of worded it better though. I do not plan on reusing my old block... It would cost to much to tear it down then have magnafluxed,blueprinted and checked and reassembled. I want to stayin the same horsepower range. I was thinking of a DSS Shortblock or a Coast High Performance short block... The issue is price... I think I can get a stock shortblock for a better price... Just having a hard time of locating a place to buy or whether to go with a bored shortblock or a stroker shortblock. What would the advantage of each type of short block be. i.e. How does a Stroker short block compare to a Stock bored short block in horspower performance, and reliability. What are some of the disadvantages and are there any problems I should be aware of when making the swap.

 

[Michael Yount]

As long as you use quality stroker components, and the machining/assembly is done carefully/competently, there's nothing reliability-wise to be concerned with. If you simply want to stay in the same range you are now, I can't see spending the money for the stroker - unless you want to make the same power you are now with even less stress on the motor. So I think I'd zero in on a solid short block in the 306 size - the other thing I'd do is bump the compression ratio a bit. You should be able to specify the ratio/pistons you want, and getting it up around 9.75 or 10:1 will make it more efficient/torquey, while still being able to run pump gas.

 

[SmockDoiley]

Hawaii racing has some great products for good prices. They have a 302/306 for 1400 using 10:1 forged pistons, and new roller block. Or the 327/331 for 1895 using new roller block, and 10.5 forged pistons. Each case its $100 more for the overbore since these are new blocks.

 

[Michael Yount]

Hey Smock - is Hawaii racing in Hawaii? I'm guessing shipping costs (the blocks have to come there from the mainland, and then be shipped back to most of us) would make them uncompetitive with most mainland-based builders.

 

[Rick 91GT]

I believe Hawaii Racing is based out of CA...

In each case what rod and crank are used? If you get a aftermarket cast kit you get a better quality crank and rod, with full floating wrist pins.

91StangLX, where are you located?

 

[SmockDoiley]

Each engine uses aftermarket forged pistons and of course the rods in the strokers are the aftermarket stuff. I'm sure the 302s use stock length rods. And yes they are based out of CA. They have a great deal on 351 blocks right now too. They are prepped machined 351's that are bored honed, decked and even clearanced for strokers. Ready to use for $695. That aint bad for a fully prepped block with new cam bearings, and freeze plugs.