What kind of HP from a 3.1L N/A stroker?

[Guest GaryZ]

Curious as to the horsepower (dyno) numbers members may have seen from 3.1 L N/A stroker engines.

[Dan Baldwin]

Here's what mine did (rwhp) this past June, after being rebuilt:

 

 

That's with 11:1 CR, on 93 octane pump, btw. It broke up above 6200 because I had to use the stock points, as my 280Z ignition failed the day before (durn). With a new Pertronix Ignitor installed, it now pulls cleanly up to my self-imposed 7000rpm MSD 6AL rev limit.

[Guest GaryZ]

Thanks for the info Dan. FYI, the one we are getting back from Rebello has 347 hp @ 6900 and 280 ft-lbs (engine dyno) but it's strictly for racing.

[johnc]

3L NA engine

 

Engine dyno

305hp @ 6,600

257 ft. lbs @ 5,600

 

Chassis dyno

279hp @ 6,700

234 ft. lbs @ 5,700

[JMortensen]

Dan, how come your hp and torque don't cross at 5252? Just curious.

 

Jon

[KiD-ViD]

Dan' date=' how come your hp and torque don't cross at 5252? Just curious.

 

Jon[/quote']

 

they do...but the HP and TQ are on different scales. look at the right and left sides of the chart. where HP is 250, TQ is about 225.

[JMortensen]

Thanks.

 

Jon

[Guest MistressMotorsports]

My engine hp numbers are similar to John C's, with a high compression 3.0 liter. If you wanted a streetable stroker, maybe figure 20-40 hp less for less compression, depending on where in the rev range you built your peak power. My car is a dog under 4k, but it's a race car. If I was building a street car, it would be more flexible down low, most likely at the expense of peak power.

 

If you are looking for an engine builder, let me know and I'll hook you up with the guys who did mine. Pretty reasonable.

 

Mike

[Pyro]

I would think it would depend greatly on what compression and which cam your 3.1 liter engine ends up with. And of course, how well the efi or carb is tuned.

 

With all things the same (cam, cr, exhaust, intake, etc) you can only expect about a 11% increase in HP and torque over a L28 engine or a 30% over a L24 liter engine. The 11% and 30% is the amount of increased displacement over the L28 and L24 engines.

 

A 3.1 liter engine will have a higher compression ratio because of the larger piston volume and the same CC head as the l28, and therefore will pick up a little more power.

 

A stock 81 to 83 L28 will make about 145 hp and 150 ft lb of torque so a 3.1 liter will do about 165 hp and 170 ft lb. If a bigger cam and more fuel is delivered then a 3.1 can make some big numbers as seen in the previous posts.

 

A L24 would make about 200 hp and a L28 would make about 230 hp if both engines were setup like the 255 hp 3.1 liter that is shown on the dyno above.

[Guest GaryZ]

John, thanks for the engine/chassis numbers--that type of comparision will be particularly useful 'down the road' for us. Obviously there are alot of variables but I think the numbers are about what one might expect ( 10% loss).

[dapiper]

Brian Wilmots stroker pulled 185HP @ 5600 RPM with triple webers on 9:1 CR on my DynoJet, mild grind.

[johnc]

are about what one might expect ( 10% loss).

 

You can't compare chassis and engine dyno numbers even to compute drivetrain losses. And my 240Z would be a bad example of the breed. I've done a lot to reduce drivetrain loss including a Quaife sequential dog box with straight cut gears.

[Guest GaryZ]

John, my setup is nearly the same as yours, but I know what you mean.

[Dan Baldwin]

Let us know what you make on the rear-wheel dyno, if/when you dyno it. For reference, I know of a 3.1 that did 305 on the Rebello engine dyno and then made 235 rwhp on a dynojet dyno. But of course who knows if the owner/installer had it properly tuned...

 

FWIW, my car only did 106.5 in the quarter, which would seem to indicate a lot less than 255rwhp. I was having some fuel pressure issues that evening (clogged filter), though, and my subsequent runs were at 103, 100, and 99. But I also wonder if the dyno I go to might inflate the numbers a bit to keep the customers happy.

 

Anywho, 347 is the biggest NA L6 number I've heard, should make for one fast Z! What organization/class are you running with it?

[Guest GaryZ]

Hi Dan: yeh, I know all the variables in engine vs. chassis dyno's, but hopefully the original numbers are reasonable and will be reflected later. My past experience with Dave at Rebello is that his dyno is honest but I have no idea how those guys actually 'calibrate' the things.

 

I plan on running it in the local version of NASA called PASA (Professional AutoSports) or maybe sometimes in SP with SCCA. I think Rebello calls it a TransAm engine, so it might be legal in vintage...don't know.

 

When I run the numbers it should be capable of a mid 11s at 130 mph in the quarter, but of course it won't be geared for such. The weight with driver is just over 2300 lbs so it should be interesting!