Ok, my engine builder told me to expect around 425-450 HP out of my motor. Does that sound correct?? I know I will hear comments about the heads, but they are machined to flow extremely well.

 

305 heads have very small valves and not the best ports. Even ported, they will not flow what a aftermarket head will flow out of the box.


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89rs w/a 400, some aluminum things and a 4.10 gear

 

I dont want to put down your engine builder, but even John Lingenfelter (:hail: ) cannot exceed 1.4 hp/ci still be manageable on the street, and with a 305 thats 427 hp. Also, cfm is the killer of hp, and the stock heads will not flow to that extent. AFR even numerically but cfm to hp, some sort of formula. Also, that Holley will not pass emissions in you '89.

You may still have an excellent motor, built by a great builder. But I would be weary: It should be him that is telling you these thing, not us. And, fibbing on the estimate is not what I would like to see out of my builder, but I am my builder!

Plus, if he is porting your heads: 60 $/h for 10 h, you could by some aftermarket heads!

 

I'd say that your engine builder is a little bit over the top... 375 hp seems more like the reality here. Hopefully the large cam will bleed off enough compression to let the engine run. A compression ratio of 11.5 to 1 with iron heads seems like a disaster waiting to happen... you'll have to constantly adjust the timing, carb and solid lifters to make sure that detonation doesn't occur. I take it that this car won't be run on the street?

Bolt on a good set of aluminum heads and you'll see over 400hp... get a knock sensor at the same time.

 

Au contraire, mes amis!

I think the 425 hp estimate is pretty good. Those 305 heads can be made to flow about as good as a set of Vortecs, whether people like that or not. And Vortecs will easily support that kind of hp.

 

and also, those are only 305 heads, not sure who it was up there quoting lingenfelter, but his 427 cid ls1(actually 428) puts 1.3 hp/liter, at a conservative 550 horse advertised, and thats na, the turbo 383 lsi puts out 650, again conservative. both combinations are exceptionally durable and streetable. oh, and 450 horse is only 1.26 horse per liter, its a 355 cid engine, just to let you know. i believe with the correct combination, premium unleaded, and a large bottle of octane booster, you can pull the 450 without throwing a head through your hood. good luck.