I put my car together with an AR Racing motor. It was rated 425 hp with aluminum heads and roller rockers. It ran fairly well but it was recently detuned after a series of minor changes. I didn't tune it because I wanted to send it to get tuned up by some local guys with a dyno. They checked the valves, curved the distributor and jetted the carb. The bad news first...it seemed far below stated horsepower. The peak rear wheel horse power came in at 280 (through the last 2500 rpm). The good news is that it went in at about 230 rear wheel hp and gained 50hp. the improvement is amazing. The car feels about 1000 pounds lighter. I recently got the suspension adjusted after replacing the suspension bushings, brakes, shocks, and rear spring. The combination of the two improvements is amazing. Plus I got that 140 mph speedometer installed in 20 minutes as claimed ($60 at http://www.redlineg.com I am obviously having far to much fun. (all this following 9 mos at the body shop!)

Anyway, with regards to the AR motor, I would have expected more rear wheel horsepower but I have no way to know if my expectaions are realistic. I am running with a mechanical fan, water pump, and fuel pump, no AC, dynomax headers, Holley Street Avenger 770 carb, MSD distributor, no cats, bullet mufflers ...

I am not unhappy with the motor though since it hauls a_s and sounds great. The "dyno tune" was well worth it! It is amazing the acceleration at all ranges. Like nitrous all the time.

:party:




[Modified by Marc80, 12:00 AM 10/9/2003]

 

Thanks for the post Marc80. What engine combo(CuIn, heads, pistons, cam) did you get from AR? I know nothing about dynos and what make up the HP at the rear wheels, so maybe with your information and other's input there can be a good discussion here.

 

as stated in the other thread... get rid of the mech. fan and the mufflers (run straight pipes).. and you'll get easily 30 - 40 RWHP more..
Read my post in the "other thread"...

Are you running AT??? If you do - that's where most of your horsepower goes... Especially TH400's eat up a lot of horsepower... The drivetrain loss is somewhere around 30 - 35% with a TH400... I had a engine that was dynoed for approx. 435 flywheel horsepower.. but just dynoed for just below 300 RWHP. This was on my '69 with AT (TH 400) and the engine was well tuned..

 

ENGINE SPECS: (AR's build sheet)
Edelbrock RPM Chevy 355
stated: 425hp @ 6100 rpm, 422 ft. lbs. @ 5300 rpm
Block: Hi Tin, 2 bolt main, race prepared, bore was torque plate honed, dynamic balanced
Pistons: Keith Black hypereutectic pistons 9.5:1
Nodular crank
Childs and Albert dura moly file fit rings
GM 5140 Forged steel pink rods, shotpeened
ARP wavelock rod bolts
Clevite tri-metal 77 rod and main bearings
Comp cams XE extreme energy hydraulic cam set
(110 LSA, 488/490 Lift @ 520/522 w/1.6, 226/228duration @ .05”
Cloyes roller set
Comp cams cam locks, Comp cams chrome-moly pushrods, Durabond cam bearings
AFR showpolished dual plane intake
Edelbrock RPM aluminum heads: Stage 1 port, bowls blended, Stainless 2.02/1,6 valves, 1.225 springs, 7/16 studs guide plates, chrome moly retainers
Lunati hi performance roller rockers 1.6 ratio

Other:
Carburetor: Holley 770 cfm street Avenger
Distributor: MSD with internal electronic ignition
Air filter: K and N drop base 14"
Dynomax Ceramic coated headers
No Catalytic converter
Dual exhaust through Bullet mufflers -w/crosspipe
Vehicle weight: 3000# (stock at 3200 lbs, now with alum head, no stock manifold, alum intake, no spare tire, 32 lb lighter rear spring, removed smog equiptment… -an estimate)

Rest of Drive train
TCI TH350 with heavy duty Sprague
Anti-ballooning 2400-2800 Stall TCI Breakaway Converter
Transmission gears 2.52, 1.52, 1
Stock 1980 Differential with 3.08 Gears





[Modified by Marc80, 12:18 AM 10/14/2003]

 

IMO if you would slap that engine combo on an engine dyno you wouldn't even get 425 HP. If it was that easy people would be building 400+ HP motors all day

IMO that combo is more like 350 - 375 or so HP, I don't see any component that would justify a claim of 400+ Hp, the compression is not that high and the cam you have is on the long side, it's designed to make power high in the rpm band. Did you rev it to 6100 rpm?


[Modified by Twin_Turbo, 6:54 AM 10/10/2003]

 

Yes I probably have had it over 6000 rpm, although to hold it there one would obviously be flying. The engine is strong. It will spin the tires from the start and power builds without really peaking for as long as one can handle the speed. It will be great for hiway, especially with the 3.07 gear, but has PLENTY of power at lower rpms too. I may try to find a electric fan and try to gain another 10 hp at low rpm. The ones at ecklers are around 500 but am hoping to find one used for under 100.

Overall I am happy ...I just expected that it would dyno a little highter. Still at 280 rear hp who can complain -compared to stock!

 

Put in a different rear gear, if you think its moving fast now, you'll crap your pants then. I am not sure that your stall is really matched to your rear gear or cam but I bet someone will know.

What are the torque numbers? both stated and dyno. The seat of the pants feel is from the torque....HP is really overated, just the more horsepower that one claims, the more torque they are also getting which makes the difference off the line !


[Modified by ylose, 7:11 AM 10/13/2003]