Production Fit engine track test

[bhayes]

Looks like HPD has started on-track testing of the "production" version of the Fit engine.

http://hondaracinghpd.blogspot.com/2...ow-122809.html

The comments about how responsive it is are interesting.

[dc]

Similar response from the guys who drove it at the 40th this summer. That new-fangled fuel injection thingy is kinda cool, eh?

[Bill Steele]

I converted a 356 Porsche from dual carb to EFI (Megasquirt ECU, etc.). The biggest single impression was how much better the throttle repsonse was compared to the carbs. No more power, but much crisper throttle response.

[Matt King]

I had the interesting experience of back to back seasons of racing in a 5.0L Mustang after converting it from a Holley carburetor to EFI. The only parts I changed were the intake manifold and related fuel system parts. The engine made within 1 hp at peak in both configurations but picked up 35 lb-ft of torque at peak and up to 40 in some places lower in the curve with the EFI system. In the same car with the same driver, it was up to a second a lap quicker at every track I ran the car at. I always considered myself a "carburetor" guy until I saw the light.

[stonebridge20]

The biggest single impression was how much better the throttle repsonse was compared to the carbs. No more power, but much crisper throttle response.

It's nothing a few hundred pounds of lead won't cure!

[dc]

Mike, I think Jeremy's car is the one that needs the lead.

[stonebridge20]

Mike, I think Jeremy's car is the one that needs the lead.

Doug, The speed in that car comes from a talented driver with nuts the size of
your head, good prep (except for wire terminals) and a brilliant engineer!

It didn't come from some rule change.

BTW: The lightest we can get the DB6 is 11lbs over minimum, as long as it's full of water.

[Dennis Valet]

Nice to see they are staying involved with the process

[TimW]

BTW: The lightest we can get the DB6 is 11lbs over minimum, as long as it's full of water.

Really? My DB6 is 874 wet with no fuel and a stainless floor...which makes for a 210lb driver plus gear to be right at limit. Why is yours/his so heavy? I can't imagine you guys weigh more than me...

[VehDyn]

Perhaps its the brilliant engineer. Does he ride along like the old days?

[stonebridge20]

Really? I can't imagine you guys weigh more than me...

210lbs,................Um,..........I wish!

[Roland V. Johnson]

Why, is someone really saying that the two engines just might have different characteristics? That's not what was advertised.
Sorry, my bad. I know that the SCCA is going to clear up that discrepancy with a restrictor plate or ECU programing.

[R. Pare]

Sorry, but "equal response" was never claimed. Fuel injection and an ECU will always respond faster and better than a 50 year old carburator setup - and no amount of reprogramming and restictor sizing will negate that difference and keep the engines even close in their HP curves.

[Roland V. Johnson]

Dang, Richard That's exactly what we have been saying all along!!!!!

[Bill Steele]

I was looking at my throttle trace from last season from my CDS system. It samples pretty fast. Looking at the traces, I am basically completely on or off with so little part throttle, with the exception of throttle blips for RPM matching on down shifts, it seems I probably could use a switch instead of a throttle pedal with little difference. I wonder if the improved throttle response likely present in the Fit install will actually translate into anything meaningful on the track?

[Roland V. Johnson]

Bill, you can define better throttle response as, more HP when I ask for it, can't you?

[Bill Steele]

Bill, you can define better throttle response as, more HP when I ask for it, can't you?

Roland, I guess you probably can, what I don't know is how much of a difference it makes in actual time on the track. I mean, I hear guys throw around seconds per lap for all sorts of things. It has always been my experience that once you get to that pretty edgy white knuckle lap time, tenths even, are pretty hard to come by regardless of the tweak being discussed.

[Rennie Clayton]

Bill, you can define better throttle response as, more HP when I ask for it, can't you?

Nah, it's a matter of timing; with the Kent, you just have to anticipate the response of the engine and mash with appropriate lead time. Kind of like turbo-lag in the old F1 / Group C days, only less sexy... more like tractor-lag, maybe.


Cheers,
Rennie

[RussMcB]

Sorry, but "equal response" was never claimed. Fuel injection and an ECU will always respond faster and better than a 50 year old carburator setup - and no amount of reprogramming and restictor sizing will negate that difference and keep the engines even close in their HP curves.

Couldn't you program the ECU to match the carbed engine's performance, even if that meant un-optimizing it?

[fezzic181]

The lag caused in a carb is from the time it takes for the air in the throat to first accelerate after throttle opening. Once the air moves faster you get the pressure drop increase that now has to accelerate the fuel in the main jet. This all takes a lot more time then the ecu saying hey open the injectors and push with 50 to 100 psi instead of the 1 or 2 from a carbs vacuum change. You'd be building an ecu noone has ever built cause getting rid of that delay was one of the reasons to build fuel injection in the first place.

Yes it could be done but now you start throwing dollar signs at it. Which of course is exactly the opposite point of this motor in the first place.

Another thing the injectors do is you get pretty much the same size fuel droplets from idle to WOT. That may well make more of a difference then the delay in fuel delivery. A new injector design of course would be insanely price prohibitive.

[Daryl DeArman]

Bill, you can define better throttle response as, more HP when I ask for it, can't you?

The IMPORTANT difference is that nobody is telling you that you can't "ask" for it sooner than you need it. In fact, I'd guess that most of the front half of the kent field already do so even if they aren't aware of it.


It seems to me that the pro-Fit folks could also complain that an instant throttle response is a disadvantage because they are going to spin more in the rain...

Couldn't you program the ECU to match the carbed engine's performance, even if that meant un-optimizing it?

I beleive the ECU is already un-optimized to get HP/TQ levels LOWER than the motor creates in a stock Fit. I'm sure they could dumb it down moreso if Kent lovers cry too long and loud.

[dc]

I beleive the ECU is already un-optimized to get HP/TQ levels LOWER than the motor creates in a stock Fit. I'm sure they could dumb it down moreso if Kent lovers cry too long and loud.

Nope, that will be done with intake manifold restrictor plates—which I don't even want to get into right now.

[John Robinson II]

I beleive the ECU is already un-optimized to get HP/TQ levels LOWER than the motor creates in a stock Fit. I'm sure they could dumb it down moreso if Kent lovers cry too long and loud.

My understanding is that the ECU is already optimized and the restrictor is being used to obtain the desired hp. Hence, altering the ecu program will only make it worse.
John

PS I heard that the kits are about to ship, I cant wait.

[Daryl DeArman]

I stand corrected. The dyno plots that were posted here sometime back were lower HP than stock. I wrongly assumed: 1)that the ECU was non-stock 2)it was dyno'd without a restrictor and 3) that a stock Fit would have produced better numbers on the same dyno under the same conditions.

[Dave Gomberg]

The FIT for FF as dynoed and as it will be delivered has a non-stock ECU. It was dynoed with several restrictors. The stock fit engine (as delivered in the street vehicle) is advertised at 117 hp/ 106 lb ft.

Dave

[gtomlinson]

PS I heard that the kits are about to ship, I cant wait.

They're shipping alright....my DB-1 kit is in route as I type.

[ric baribeault]

tim, i think jeremy could get down to weight if mike would lay off the donuts and stop leaning on the car

[guudasitgets]

"flat black helicopters are beginning to circle

[RussMcB]

"flat black helicopters are beginning to circle

Hey "b", where's "g"? :-).

http://www.apexspeed.com/forums/member.php?u=8159