View Full Version : 427 build, LOW HP #s

11-11-2011, 04:27 PM
So I just finished building my new motor and wasn't very happy with the hp numbers. On a mustang dyno it is putting down 430hp. Here is what the engine is:

427ci ls motor
235 trickflow heads milled
ross pistons -20cc
eagle h beam rods
beck sheetmetal intake
95 mm tb
large hydraulic roller cam

all through a turbo350/4500 vig stall/9inch with 373's

Any ideas? I figured I would be around 500rwhp...

Maybe compression is to low?
Or stall eating up alot of hp?

11-11-2011, 08:04 PM
What is your compression? How good is the tune? Does it feel strong?
Lots of questions to ask. I try not to get too caught up in dyno numbers as they can vary drastically from fron dyno to dyno. As long as you are sure there are not issues with it, take it to the track and see how it performs.

11-11-2011, 08:39 PM
you do have a big stall through a th350 and 9 inch.

though my ls2 h/c/i stalled a4 is making similar power on a mustang dyno so i dont know.

whats your tuners advice?

11-12-2011, 09:59 AM
compression is 10.5:1
tune is spot on

11-12-2011, 11:16 AM
compression is 10.5:1
tune is spot on

Just for giggles and this applies to any engine thats missing power, do a compression test..

When you say large cam, how large are we talking? between 230 and 240 duration? higher? how does it drive? is it strong?

theres a bunch of variables, if your tune is spot on then the problem could be valve timing, which in turn cause many other problems, including providing you with inaccurate compression figures..

check your compression.. and go from there...

11-12-2011, 05:06 PM
cam is a 250/258

11-12-2011, 05:18 PM
bore/stroke size??

11-12-2011, 11:30 PM
4.130/4 inch stroke

11-12-2011, 11:41 PM
well mustangs are known to read incredibly low, so lets say on a regular dyno you would of had about 480, still seems a little know,

was your converter locked? if not that could take away 50 hp or better

11-13-2011, 12:09 AM
Car running out of fuel? Low on timing?

Orange Juice
11-14-2011, 09:52 PM
Would think it would be higher with that much cam, really you need to take it down the quarter and see what it does.

11-15-2011, 10:25 PM
-20cc dish really killed power potential, plus auto, plus 9". Put some boost thur it

King Nothing
11-15-2011, 10:33 PM
-20cc dish really killed power potential, plus auto, plus 9". Put some boost thur it
So I wasn't the only one readin -20cc and thinking wtf if you have no blower. Why would you choose those pistons if your not going to run a blower? Unless your planning on a blower

11-15-2011, 10:58 PM
Even with low compression he should be making more power then that. Stock cube LS1's make that even with stall and TH tranny. Somethings definitely wrong...just my 2 cents.