Crossflow dyno results

[Kitcat]

1700 cc Super Sprint w/ 135 advertised horsepower:

 

93.5 hp

91.5 lbs torque-nice and flat from 4K on and pretty good from 3500 RPM.

Test done at Paul's Automotive in Cincinnati this morning.

 

Don't ask for the actual charts, I put them in my shirt pocket and as soon as I got back on the highway the vacuum at 70 mph sucked them right out, never to be seen again.

 

Ambient temperature 80 degrees, humidity unknown.

 

Am I surprised/ disappointed? Neither. When I took my "129" hp Miata there it made 98 hp, and it was 100 cc bigger and of a more advanced design. I sort of expected 85 hp, so I was happy.

 

What did I learn? Well, the air fuel ratio was 17.5:1 (Yikes!). So it's going back to spend some quality time on the dyno with their carburetor expert. I should pick up a few missing ponies in the process too.

 

Stay tuned (no pun intended).

[xflow7]

Wow. Was it that lean across the board, or only in a specific regime? Did you get any A/F measurements at part throttle?

 

Can you give a rundown of the jetting you are currently running?

[Kitcat]

Good questions, but I don't know.

 

Once they redo the jetting/tune I will get the details. I am taking it back next week & then will be on vacation a coupla weeks so won't have details for a while.

[stevet]

Not too surprising as the 135 hp 'advertisied' is thought by many to be somewhat exaggerated - engine builders especially. I had my crossflow rebuilt in 99 (unleaded conversion, plus new pistons, bolts etc.) and it made 109hp at the wheels.

 

Still a lot of fun though

[bball7754]

The St. Louis Lotus club had a sort of "dyno day" over the Labor weekend. Pretty low key - everyone just cycling through the dyno - 3 pulls and you were done.

 

My 1700 Crossflow started life as the 135 HP spec, then had the cam changed to the 244 which I was told put it in the 150 HP category - at least in theory.

 

As you can see (maybe - not as sharp as I had hoped), I managed 107 HP, and 97 ft. lbs. I think if I'd gone to 7000 rpm (or close) I might have made it over 110. Didn't measure the AFR, although I may go back and have them check that also. I think I'll wait until the temp is in the 40's - the Webers love that cold air.

 

http://www.usa7s.com/aspnetforum/upload/1378673624_Crossflow_Dyno_09012007.jpg

[Mandurath]

Usually a fair difference between at the crank and at the rear wheel. So i would say that you motor is probably close to spec.

[lowflyer]

Agreed, you can generally count on about a 15% loss for drivetrain drag from flywheel HP.

[slngsht]

Agreed, you can generally count on about a 15% loss for drivetrain drag from flywheel HP.

 

These losses are WAY more than 15% if the advertised engine power numbers are right.

 

For reference, my LS1 was advertised at 345hp from the factory, and produced 298 at the wheels, which works out to 14% loss - inline with everybody's estimate of 15% loss through the drivetrain.

[WestTexasS2K]

My driveline loss seems a little high to me. It is supposed to be 240hp and dynoed 186 when it was NA.

[slngsht]

My driveline loss seems a little high to me. It is supposed to be 240hp and dynoed 186 when it was NA.

 

Is that in line with what S2K folks see with their cars?

[Kitcat]

I got the car back today. Wow, it runs so much nicer! No coughing, spitting, popping, backfiring or wheezing. It's almost like a fuel injected vehicle. The guy who tuned it wasn't there so I have no details as to what he did except the power level is the same per the dyno: 93 ponies, just a lot smoother delivery and the correct air/fuel %.

 

The work sheet shows it had a damaged venturi that had to be replaced and some parts were loose and some jets replaced.

[johnh]

I'd be curious to know the details of your current carb setup wrt jets, etc.

 

---john.

[powderbrake]

My driveline loss seems a little high to me. It is supposed to be 240hp and dynoed 186 when it was NA.

 

I dynoed mine the same day as bball7754. It was on a Mustang dyno. Quick and dirty set-up, no fuel -air readings.

 

I dynoed 176hp. The operator said he cranked in a guess of a 12 1/2 hp loss for wind resistance at 50 mph, which the computer uses to calculate rear wheel hp...? I assume the computer adds 12 1/2 hp of load that isn't displayed, or rather that the hp is really 176 + 12.5= 188.5. with 188.5 and 15% losses, that would be 222hp, which is reasonably close to the factory 240 hp.

 

The Mustang dyno has you run in a gear that is 1:1, and hold it at 2500 rpm, so the dyno can claculate engine rpm from the speed of the roller. Well the Honda transmission doesn't have a 1:1 ratio. 4th is 1.16, and 5th is .96 so I am not too sure of the accuray of the whole setup. The Mustang does not sense the engine rpm with a pickup from the engine.

 

The Mustang dynos have a reputation as heartbreakers, no one is ever happy with the results ( which the operator concurred with). They have the advantage of being able to hold a horsepower load for tuning because they use an eddy current brake, wheras the Dynojet is an inertial load and can't hold steady load on the engines. The place we were at specializes in tuning on Fords, and stated that they don't worry about the absolute hp number, they only use it as a baseline for the tuning, to see the improvements.

 

I wasn't going to run it on the dyno, I just went there with the St.Louis Lotus club for their Dyno Day, but once I was there they talked me into putting it on the dyno, so here I am... still guessing what is the REAL hp?. I should not really care, because the car runs perfectly, and has more than enough power to exceed the capability of me as a driver.

 

There were Elises and Exiges, and Esprits, and a Cadillac CTSV, in addition to my Ultralite and Steve's Caterham, but mine was the LOUDEST!

[Kitcat]

My test was also on a Mustang dyno at a place that specializes in Ford V-8 engines. Hey, the Crossflow is a Ford engine!

 

I continue to be amazed at how nice it is running: starts right up, no issues while engine warms up, much more drivable between 2000 RPM's and 35000 RPM's, etc.

 

The Big test will come after I take it on a trip: we'll see if the dreaded large gas deposit on the clam/windshield/rear wheel arch occurs.

[Mandurath]

35,000 rpm!

[Kitcat]

Yes 35,000 RPMs. It's a pretty trick set-up, tho the engine life is reduced considerably:).

[WestTexasS2K]

35,000 rpm!

:rofl:

[slngsht]

 

I dynoed mine the same day as bball7754. It was on a Mustang dyno. Quick and dirty set-up, no fuel -air readings.

 

I dynoed 176hp. The operator said he cranked in a guess of a 12 1/2 hp loss for wind resistance at 50 mph, which the computer uses to calculate rear wheel hp...? I assume the computer adds 12 1/2 hp of load that isn't displayed, or rather that the hp is really 176 + 12.5= 188.5. with 188.5 and 15% losses, that would be 222hp, which is reasonably close to the factory 240 hp.

 

The Mustang dyno has you run in a gear that is 1:1, and hold it at 2500 rpm, so the dyno can claculate engine rpm from the speed of the roller. Well the Honda transmission doesn't have a 1:1 ratio. 4th is 1.16, and 5th is .96 so I am not too sure of the accuray of the whole setup. The Mustang does not sense the engine rpm with a pickup from the engine.

 

The Mustang dynos have a reputation as heartbreakers, no one is ever happy with the results ( which the operator concurred with). They have the advantage of being able to hold a horsepower load for tuning because they use an eddy current brake, wheras the Dynojet is an inertial load and can't hold steady load on the engines. The place we were at specializes in tuning on Fords, and stated that they don't worry about the absolute hp number, they only use it as a baseline for the tuning, to see the improvements.

 

I wasn't going to run it on the dyno, I just went there with the St.Louis Lotus club for their Dyno Day, but once I was there they talked me into putting it on the dyno, so here I am... still guessing what is the REAL hp?. I should not really care, because the car runs perfectly, and has more than enough power to exceed the capability of me as a driver.

 

There were Elises and Exiges, and Esprits, and a Cadillac CTSV, in addition to my Ultralite and Steve's Caterham, but mine was the LOUDEST!

 

adjusting power for wind resistance doesn't make any sense to me, unless he's trying to run your engine at very light load to simulate on the road fuel economy. power at the rear wheels is what it is, even on a windy day

[slngsht]

35,000 rpm!

 

And that's before it hits the power band

[xflow7]

 

adjusting power for wind resistance doesn't make any sense to me, unless he's trying to run your engine at very light load to simulate on the road fuel economy. power at the rear wheels is what it is, even on a windy day

 

:iagree:

 

Only thing I can think was it was intended to be a correction for some kind of ram effect, but even that doesn't hold; at 50mph you're talking a fraction of a percent of incremental air flow.