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1500 question.

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maddy

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I’m tired of driving steep grades and the car slowing down. I’m going to get more power out of my 79’ 1500 midget! Again, it’s not to race but to have fun with. I have 2 options that I will be going with and was hoping for some advice as to which option might be the best route. I know that the lower end on these engines is a tad weak, so I don’t think I should be combining my 2 options together. I’ll be doing it this winter.

Here they are:

#1, Leave the engine with the stock 7.5:1 ratio, balance the crank, port the head and add a small turbo, which I have on hand. I’ll make sure the single SUHIF4 carb is set for best running, or go up to a SU6.

#2, Change the bore to 30 over with 9.1:1 ratio flat pistons, balance the crank, port the head.

I think #1 will give the power that I want while getting good mileage (if I don’t stomp on it) not having to go with high-octane gas. I also think that #2 would give me a wider band of more power, but I’ll have to go with higher-octane gas and I’m not sure what would happen to my mileage.

Thanks, Mark
 
I would not worry to much about the lower end being weak- it is what it is. And it is fine. Your lacking power could be a sign you need to do the head... at least do a leakdown test and see what you have.

My car climbs hills just fine. in fact it climbs better than my 06 Matrix

current specs
.02 over
low comp pistons
th2k cam
twin hs4
4-2-1 header/2inch pipe/harley muffler-fully baffled
3.9 rear
consistent 30+ mpg

turbo could be fun... You should definitely add a cam to your list. Stock cams were a bit detuned to meet smog standards.



mark
 
Go 9 to 1, and don't port. You want torque so keep velocity high. If that isn't enought, you can still do a turbo w/ 9to1. There is a guy doing 11 to 1 turbos on Ferraris in Dallas. You'll have to go w/ MS or some other programamble stand alone injection.

If you go turbo, keep the stock cam in it.
 
Don't worry about an SU6 carb - it will be too big for the engine. a "4" is more than you need. There is some math about Carbs needing to be a little smaller to work better. I kind of understand it, but, certainly my HS4 had to be blocked off some to get it to run right
 
Down here in sunny Johannesburg

I agree with Mark the Silent Unicorn. I have a book on tuning and the 4:2:1 exhaust increases HP by 15%, removing the mechanical fan 5% and foretunatey for me I have twin SUs
 
SAMidget said:
Down here in sunny Johannesburg

I agree with Mark the Silent Unicorn. I have a book on tuning and the 4:2:1 exhaust increases HP by 15%, removing the mechanical fan 5% and foretunatey for me I have twin SUs
Click to expand...

Really? I though a header was only worth 2-3 hp on these engines.
 
Before you do too much to the engine try putting a 4.22 differential in it and see if it climbs hills enough better for you to be happy- or do both.
BillM
 
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