My local autocross club had a dyno day at a local shop. I have to admit I was pretty disappointed with my results. On the first pull it made 110hp and 119ft-lbs of torque at the wheels. If you figure a 15% drive train loss it would come out to about 126hp and 137ft-lbs of torque at the flywheel. On that pull all of the plates on the Super Trap were removed. On the second pull with all of the plates I had put back on it made 103hp and 113ft-lbs of torque.
I guess a little back pressure doesn't help here. I wasn't sure if the 3" exhaust was going to be too big. I guess it isn't. They say that 18 to 20 plates is like having an open exhaust, so I ordered 6 more plates (they only come in packs of 6 or 12). I have to stay below 96 db to meet my clubs noise requirements. I don't know if I will with all of them on.
The first pull was the only one he was able to take an air-fuel reading on and he said it was quite rich and if I leaned it out a little it would help. I pulled the air filters off and noticed that they were VERY restrictive. The opening of my 38mm Mikunis is 56mm. The filter couldn't have hade more than a 40mm opening in the rubber. So I have decided to go with velocity stacks instead. This should help improve airflow and lean it out. I am going to try to build an air box that I can put around all of them and use a K&N flat filter on top. It will be able to pull cool air through the louvers in the hood.
Also I still need to degree the cam. I called Racer Walsh to try to get a specification sheet that told me exactly where the cam should be degreed, but they didn't have anything they could send me. I am going to pay somebody locally to help me with this step.
After I get all of this done I will put it back on the dyno and post my new results. I hope to have some where around 130hp at the wheels. I guess I will be stuck below 150hp until I can get a lot of head work done. Head work is very spendy and it is getting harder and harder to find parts for these 2 liter engines any more.
Greetings,
After looking at your Dyno sheet, I don't see a peaky power curve. I would assume you want more power (HP) at a similar delivery curve for AutoX. In my experience with my own 2.0L , I can't expect much more than 160 to 175 at the Crank , with twin Dcoe 40's and 10:1 Trw pistons, with Norris 288/ 450 cam.
My motor is adequate for AutoX , the real challenge is getting the car to handle, and to tweak my skills in driving it. If I Hillclimb the car, then I really wish for the 45mm DCOE's and more cam, and would give up that snappy broad torque for a screaming 5000 to 7500 punch. At 85 to 120 mph you need high rpm power.
Visit the english web sights for 2.0L engine builders Puma, Burton ,and view their concept of 2.0l Power. Keep looking and you'll find sites with video of Dyno Pulls.
Good hunting...
Pintosopher
Just to throw this out there but, aren't TRW's forged Pistons seem heavy?
That always bothered me. But I don't know what you guys have anymore for options when it comes to 2.0L pistons.
FrankBoss
Frank,
I'm sure we have other options for pistons, but my engine was built many years back ! It was a backup short block for a IMSA RS Pinto that was quite competitive for it's time. If it was prepped for a real no limits package, I'm sure that it would be closer to a reliable 180HP.
I was told by the Racer who built the engine, that it made nearly 170 HP with a large Holley 2 Barrel. It had enough power to out drag a RX-3 Mazda rotary on the uphill straight at Laguna Seca. Later the Rotary was allowed to be built with more mods, and the rest was history. I personally experienced this when I was smoked by nearly 10 seconds at a Hillclimb in Oregon by a RX3 that had a Dyno rating of 285HP normally aspirated. That car left the line and smoked the tires for 100yds and three gears and still blew all in that class away.
We 2.0L all dream of reliable 180- 200HP Normally aspirated that can run with a reasonable idle.
By today's builder standards, I believe it's possible but very expensive!
Cheers,
Pinstosopher
I see that you have more of a cam than I do. Mine is a 450 lift with 245/252 duration @ 0.050. What kind of other headwork do you have done? I am also using TRW pistons, but mine are pop-ups that raise my CR to 11:1. I run a 50/50 mix of Premium unleaded (92 octane) and 130 leaded (118 octane) race fuel. I could probably advance my timing more. How much advance are you running?
And how would my 4 38mm Mikunis compare to your twin Dcoe 40's? 175 Wheel hp would be awesome!
Greetings,
Sorry to be late in getting back to you EP, life gets in the way. The head on My motor is an unknown, I've not seen any evidence to shown extensive mods. The Old IMSA RS series didn't allow much in real head work. The short block does have crankshaft mods visible on the casting and the flywheel end is doweled to keep the flywheel from getting loose. At best it might not be a "complete " engine package. My pistons are flat top zero deck height. The engine doesn't want much more advance than the Mallory Unilite distributor and coil will deliver at the stock setting. Advancing the cam timing with the Esslinger Pulley, doesn't help much either. The size of your Mikunis is a bit on the small side for a modified 2.0L motor. I would consider a switch to 44 mikunis or jumping to 45 Weber's with the Compression ratio you have.
Keep in mind , HP isn't always the answer. In autocross , you have got to get that chassis to rotate through the various dynamics of vehicle physics in the short and violent movements of that sport, and do it smoothly. Hillclimb racing is much less demanding on the chassis setup, and you can tune a motor for top end HP and balance the chassis easier.
If you are part of EESCC, give my best to Jim & Bonnie Mueller, and anyone you know from Willamette Motor Club in Salem. Fun group of folks.
Stay Coneless if you can ...
Pintosopher