Dyno # went down with upgrades???? Help!!!
Thread Starter
Racer
Joined: Aug 2009
Posts: 275
Likes: 0
From: PEORIA IL
Dyno # went down with upgrades???? Help!!!
Ok so my 98 c5 had ls6 cnc heads and a small comp cam. Took it to the dyno for a base line and it made 330 at the wheel and 475 on the spray. Over the winter I put a set of AFR 225 heads, part # 1660 on and comp cam XER273 HR-14 in the car, ALSO a yank 3300 converter and a 3.42 gear. (before converter and gear were stock) Took the car to the same DYNO and had it tuned and now on the motor it makes 346 at the tire (small increase) and only 440 on the spray, lost 35hp at the tire on the dyno. Is the converter eating all the power up or what is the problem? I spent a lot of money on afr's and biger cam converter and gears and lost power?
Any ideas on what the problem is, the spray is the same as last year, Also ran the car with converter locked and unlocked and only made a small difference so in my opinion the converter is working fine,
Any ideas on what the problem is, the spray is the same as last year, Also ran the car with converter locked and unlocked and only made a small difference so in my opinion the converter is working fine,
Team Owner
Joined: May 2003
Posts: 23,480
Likes: 9
From: East Meadow NY
St. Jude Donor '12
IIRC, the extra gear will cause you to lose some HP on a dyno reading. 330RWHP and 346rwhp after for a H/C car seems extremely low as it is so you may have some tuning issues in general.
Race Director
Joined: Sep 2005
Posts: 11,060
Likes: 291
From: Pasco WA
Did you go with stock AFR 225 heads on a stock block 346? If so, IIRC, the 225s have 72cc chambers, so you're losing compression. Also the large port AFRs are best utilized on a stroker motor because the port velocity is lower than the 205s, and on a street driven (A/T) car should be pretty soft on low speed TQ. You need to swap heads, or have those milled, but they're still not optimal for your combo.
Thread Starter
Racer
Joined: Aug 2009
Posts: 275
Likes: 0
From: PEORIA IL
Did you go with stock AFR 225 heads on a stock block 346? If so, IIRC, the 225s have 72cc chambers, so you're losing compression. Also the large port AFRs are best utilized on a stroker motor because the port velocity is lower than the 205s, and on a street driven (A/T) car should be pretty soft on low speed TQ. You need to swap heads, or have those milled, but they're still not optimal for your combo.
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