Ok I just did a dyno run a month or so ago and had results of 474HP and 478TQ. So I went over engine recently and found some things wrong like the push rods were .50 to long ( Larry's engine marine in Tucson AZ SUCKS! "engine builders") and that actually fixed the fast drop in HP AND TQ from 5500 to redline. Now it has a 10% grade going up from 5500 rpm vs the 20% decline before and the results were I picked up 20 HP.

Next I had the heads checked and flow tested to see if they were good. Well the heads them selfs turned out physically good but the flow numbers really sucked. they flow 297@500, 309@600 and 209@500, 221@600. TF website says they are suppose to flow 338 cfm @600. These number were way off what TF's website says. The heads flow up to 20-40cfm less from 400-600 lift then there websites lift sheet.

So can a 30cfm difference make much of a hp/tq gain? how much is 30cfm worth in those lift areas? Is there anyone that can fix these heads to flow the 338 cfm@600 or better? I also plan on milling the heads soon to bump compression will that effect the flow numbers better or worse?

Since the engine builder messed up on something easy like pushrods length is there anything else that I could check that could rob more power? I am not an expert on advancing or retarding the cam but could it be possible that they they didn't put cam in right or went to far either way even though I didn't ask them to?

Pat G who built my cam looked at my dyno graph and said my HP/TQ look right on par until about 5500rpm and said that maybe I have a intake or exhaust choke in the system and that is why it is flat lining after 5500 rpm and not making the 500+ it should be making. He did say it is pretty hard to tell without looking at my tune or having the car in front of him but he said he would upgrade my current 1 3/4 to 1 7/8 and a true 3" exhaust since I have a 2.5 mid and exhaust. would just changing the exhaust gain me a 25hp bump from 5500-6500?


Any Ideas on anything else I could check before I go spending big bucks would be appreciated

 

Can you post a graph?

Same dyno used before and after? Same correction factor?

 

I don't have a way of posting the graph but another member posted it for me a little while ago under one of my threads when I was trying to figure out best rpm to shift at. Here is the link: http://forums.corvetteforum.com/c6-t...mile-time.html

Or you can give me your email address I'll send you graph and you can post it?

Yes same everything. Thanks

 

anthony@lgmotorsports.com