Changed my mind again on heads & blower, but still researching blocks...

All that stuff... and you're going to stay with NPI heads?


Not sure why they'd weigh any less than PI's.... Just go with a good set of heads as well, you can thank me later

I want to know if aluminum blocks are weaker than an iron block.

the teksid block is good for 1000+ hp so you should be ok

As was said, the Teksid aluminum block handles well over 1000hp... and it will save you over 50lbs of weight in the front end. I don't know about the underhood temperatures, but aluminum does transfer heat better than steel so that would explain it. Just make sure you have a cooling system thats up to snuff with the rest of the car. If you keep your NPI heads, I would suggest first pulling them, sending them off to Steen racing and having them ported and have the hardware upgraded. I would also choose a good set of blower cams... trust me, you do not want to keep the stock NPI cams, those will be a major bottleneck for your KB set up. With ported NPIs and blower cams, you will be able to put down some good numbers...

Definitely don't worry about the stuff you've heard about aluminum blocks... if I had money to do an engine build, that would be the first thing I would purchase. It looks like you know exactly where you're going with this project, awesome Keep us updated.

I'm so confused .... yea easy enough but...

I want an aluminum block for my GT to lighten the front end.

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Aluminum blocks causing increased under-hood temps and iron blocks making more horsepower

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I want to stick with the non-PI heads for weight savings and ease of install, and the Kenne Bell 1.7 seems to respond well to those heads

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I was going to forget about the blower and do FR500 4V heads all NA

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I can live with 500-600 RWHP in this car though.

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I think I can do that with the Non-PI heads and the KB 1.7(now the 2.1) from the reading I've been doing

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The heads are coming off the stock block, being stripped and rebuilt with all new valvetrain and blower cams. I just don't want to spend anymore $'s on PI castings or 4Valve when what I have will work just fine and give me the numbers I want.

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I would love to see the threads for these conclusions. I've never been exposed to this information.

BLK_ROUSH said:

I'm so confused .... yea easy enough but...








I would love to see the threads for these conclusions. I've never been exposed to this information.

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I'll go down the list and try to give some supporting data for each quote...

1) Fact: A bare aluminum block is somewhere between 80-100 lbs lighter than a bare iron block. Mustangs are a bit heavy in the front... you want a car to handle better you try to get as close to 50/50 front/rear as you can.

2a) I've only just started seeing info about the aluminum blocks raising under-hood temps over in the SVT forum, but no facts to support it. If you think about it, aluminum heat-sinks are used to dissipate heat on things like amplifiers, coils, PC chips, etc. Rumor is that the aluminum block allows more heat to escape from the motor into the engine bay(I guess just like a heat-sink)

2b) Fact: Iron blocks typically have less harmonic vibrations than aluminum blocks which robs the motor of its max horsepower potential.

3) Fact: (Assembled with cams and valvetrain) 4V Heads = 65+ lbs each, PI Heads = 46 lbs each, NPI Heads = 50 lbs each. So my heads weigh considerably less than the 4V heads.

4) Fact: The Ford Mustang FR500 had 4-valve head castings that can be purchased from Ford for $800.00 a head as part no.s M-6049-T46 & M-6050-T46

5 & 6) The tech-articles and dyno charts on Kenne Bell's website prove that the Non-PI heads with blower cams are easily capable of over 600HP at the flywheel with only the 9 lbs pulley on the 1.7L

7) I wouldn't waste time buying any head that wasn't ported and worked to the max. If I'm going to spend $'s on anything I want the best...so I don't want to spend $1,300.00 on PI head castings if I don't need to because my heads will do what I want. And if I spent even more for 4-Valve head castings, everything else goes up in price for valvetrain, cams, and all of the other things like computer and wiring harnesses, ignition and so on for the 4-Valve swap.

If I've left anything out I'm sure the experts will chime in and correct any of my data or fill in the blanks.