I plan to dyno my engine just for peace of mind...but for now, can someone help me guess my HP: I have an SC engine with '74 heat exchangers and sport pipes (authentic). Bought 'em in Amsterdam last year from an old rally-meister.

Secondly, I posted earlier and heard a little later, the perils of supercharging - won't be doing that now.

But 20/21 cams sound nice and durability will be good (I hope). Overall, with a 3.0, backdated exhaust w/ sport pipes and 20/21 cams, please tell me what the proposed horsepower will be of this setup? Engine is an '83, if that helps...

TIA

 

A stock 78-80 SC has about 180 HP. ROW 80 SC have 188. ROW '81-83 have 204. The SSI and Sport Muffler are rumoured to add about 10-15% more HP. I am not sure what the cams will do.

I have done the change to my '78. I use 200 Total.

So your engine should be 204 plus say 25 that makes 229, round up to 230.

I would be curious to hear of your actual Dyno results.

marc

 

My guess - 195-200hp at the wheels.

 

Guys - when I mentioned Amsterdam, I meant I got the sports muffler in Amsterdam - not the engine. I have a 1983 U.S. 3.O. Sorry if I wasn't clear.

Cam B, you're saying with the exhaust and cam changes, I should have 195-200 at the wheels, not the flywheel?

TIA

 

Sorry to burst your bubble, but there is no way with an exhaust and cams on an sc are you getting 195-200 rwhp. That, roughtly converts to 240-250 flywheel hp, and that takes A LOT of mods on a 3.2 (namely that it becomes a 3.4), let alone a 3.0. I think 195-200 at the flywheel is a far more accurate estimate.

 

Depends on what you think dyno losses are? I think rwhp x 1.1 or 1.15 - thus around 220hp. I posted my guess on RWHP because that is less open to debate... I've got a measured 245hp at the wheels and there is no way I have 1.25x that (over 300hp) from a 3.2.

A US SC is 188hp? I think. I'm only giving say 12hp for the exhaust and 20 for the cams. Maybe a little generous.

<a href="http://www.pelicanparts.com/techarticles/911_engine_rebuild/911_engine_rebuild2.htm" target="_blank">http://www.pelicanparts.com/techarticles/911_engine_rebuild/911_engine_rebuild2.htm</a>

 

ok, all the listings from the factory for the engines are not rear wheel dyno results...they are at the flywheel!

So my guess would be at best +20HP at the flywheel due to the freeflow results with the backdated exhaust...but you must consider the loss through the drivetrain.

So I would guess 190 - 195 HP at rear wheels.
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

 

Wow, we are an optimistic bunch, only 10-15% driveline loss, the industry readily assumes 15-20%. Even if we assume the best, 15%, 195 rwhp is equivalent to 229 fwhp, still very optimistic given that it is a 50 hp increase over stock. Exhaust and cams MIGHT get you 30 fwhp, therefore
I will stick with my initial estimate of 195-200 fwhp.

CamB, what did you do to your engine? If we assume the 15% loss, 245 rwhp equates to 288 flwhp, and most engine builders say that this amount of hp requires new high-comp P&Cs (therefore no longer a 3.2), cams, dual plug, exhaust and maybe mass air. If you have found some magic in the motor that we don't know about, by all means please share it!! We could all use to save a few bucks!

I am not trying to be a downer here, just a realist.

 

well I guess we are optomistic, but yeah generaly on a car with no driveline no U-joints you generaly assume about 13-16% parasitic loss from the driveline. <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

 

a source for dyno comparison numbers
<a href="http://www.edmunds.com/editorial/techcenter/horsepowernetvswheeldriven/43845/" target="_blank">www.edmunds.com/editorial/techcenter/horsepowernetvswheeldriven/43845/</a>

 

Sorry - I have no "cheap" secret - it isn't a Carrera engine! It is an SC case and (ported) heads, 98mm 10.5:1 pistons and cylinders, twin plug, early-S cams and throttle bodies with EFI. Exhaust is SSIs and 2 in 1 out muffler. Thanks to the EFI and high compression, I have more than 85hp/litre which is better than any of the factory S-cam cars, so I am pretty happy.

But it wasn't cheap . It had better last a long time!!!

I was using the 245rwhp to indicate what the dyno guy I used told me for the conversion factor. I realise 1.1x is pretty low (only 9% losses). I would believe anything in a range from 9% to 15% for a transaxle transmission and maybe as high as 20% for a car with a separate gearbox, propshaft and diff.

Subjectively, I have read of a number of people who are happy with the change to their SC from 964 or 20/21 cams.

Cam

[quote]Originally posted by Roamer:
<strong>CamB, what did you do to your engine? If we assume the 15% loss, 245 rwhp equates to 288 flwhp, and most engine builders say that this amount of hp requires new high-comp P&Cs (therefore no longer a 3.2), cams, dual plug, exhaust and maybe mass air. If you have found some magic in the motor that we don't know about, by all means please share it!! We could all use to save a few bucks!

I am not trying to be a downer here, just a realist.</strong><hr></blockquote>

 

I don't mean to dive in here, but I'm curious about my engine as well...
its a ported & polished 3.2 ['86] with web cams, chipped ecu and Bursch exhaust.

what would you estimate to the rear wheels?

 

Cam, my hat is off to you, sounds like a great motor, but I can imagine that you have some serious bucks in there! However, I think it illustrates my point. YOu got 100 flwhp from +$10k in SIGNIFICANT mods (and I know the laws of diminishing returns) but cams and an exhaust won't get you half way there.

I would have to agree that those cams have yielded nice results.

 

Yeah (on all counts!!!).

Still, I base my estimate on Noah Pollack's slightly over 200hp from a 3.0 Carrera with the same specs but slightly higher compression.

I guess it also depends how healthy the engine is to start with.