Thread: Blown Hemi

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Originally Posted by eticket

and it has to get good gas milage

I had thought about the crate motors, but was concerned about the compression ratio, I thought the crate 426s were about 10:1, and I didn't want to go past 9:1 for a blown street motor I thought was the norm, but I could be wrong.

Thanks for the help so far, but no one has given me a definitive answer yet, still looking for that "Oh it has to be ...... because of....

Mike

Blown Hemi and good guess mileage don't even belong in the same thread!!!! Blower engines should be 8.5:1 or less compression based on how much boost you want to run... Look in the PAW catalog as someone suggested, there's everything you need, nothing left to do but write the check!!!! Here's a link http://www.pawinc.com/, phone number is there, just call them up and get the thing ordered.

I'm with Dave on the gas mileage. Don't worry about it...it isn't going to be very good. It will be so much fun to drive that you will be just running from gas station to gas station anyway.

I'm assuming you are looking at 6-71 or 8-71 blowers. 6-71 is enough for a street stetup from your ideal plan.

Now the low compression is good 8 to 8.5 no problem on either style. Try for no more than 3-5 lbs boost. Even this is a lot considering that your car probably will weigh only 2800-3000.. maybe less if plastic. You will be around 400-450 hp at the wheels with out trying hard. No need for a hot cam either. Just something that has a good sound. Do have a good ignition system and fuel system and keep the advance down. There are boost controlled advance devices available. MSD

You can set it up for a single carb. Say a 750 or 800. No need for 6500 rpm on this car. Check Hot heads . There is a secton on a scoop/carb setup that is made by Garlits that has a hidden carb in the scoop. It is very cool that does just this. Edelbrock makes a blower carb with the manifold referenced power valve and correct jets etc. So does Demon.

I'd carry a spare set of head gaskets,blower gasket, blower belt and tools if you plan on any hot dogging. Both style motors are very easy to work on if you have room. You should be able to change H/G in an hour or so. I don't think you would ever burn a piston unless you are racing but if you limit the motor with a single carb, it will run out of fuel and air long before it hurts itself.

Also set up your starter switch so you can spin the motor over then hit the ignition switch. This will prevent backfires while starting and busted starters.

You will have fun with this car. I wish it was mine. Do remember if you are using all steel motor these things are very heavy so your car will be a little nose heavy. Adjust your suspension to allow for the weight and put all your stuff in the back.

Keep us posted on progress.