Fastest 5.0 (pushrod) Kenne Bell Mustang?

90lxcoupe said:

Did the car make 750rwhp? If so, it should be going faster than 9.60's unless the car weighs like 3700 pounds

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If you do the math, there are several online calculators available, a 3350 lb car reaching a speed of 143 mph in the 1/4 mile, has to make about 750 RWHP to go that fast. That is what we are basing the RWHP #s on. On the dyno, it is really hard to get an accurate # with the automatic trans. With the torque this engine makes, it is hard to get the tires to hook on the rollers, also consider torque converter flash ect and a "real" number is tough to get. In actuality, the car is possibly making more than that. The real limiting factor we have is the small 26x8.5 tire we "have" to run. We cannot leave at WOT on the transbrake, cause it just blows the tires off. We leave at 40% throttle (according to the data log) and even then that is at 12 psi boost. WOT is not seen until about 60' out. So really, if you want to bench race..........with a 28x10.5 slick, we "should be" running a low 9.4 or quicker as the car is now.

Some more interesting data log information from our last time at the track last fall. The final 3 runs were all at an identical 143.63 mph. Time slips from the track were very informative, even though the E.T's fluctuated a bit as the 60' varied from 1.50 to 1.54 on those runs, the MPH were all the same. A much closer look at the data logging from those runs found that we were hitting the rev limiter about 100 feet short of the finish. So basically we had maximized the current combination. We were already spinning the engine to 6,800 rpm, which is max for the hydraulic roller cam that we were using. That is why 2 weekends ago we pulled the heads and cam so we could upgrade to a solid roller and spin the engine at least another 500 rpm and take advantage of the cylinder heads that are on the car as well. We are thinking that an additional 100 HP is a very reasonable goal to obtain. Plus it solves the rpm rev limit issue down track, or so we hope, otherwise a different rear gear is in the works.

Currently using a 7.8" crank pulley and a 2.5" blower pulley. We do not see any boost drop off until about 6,500 rpm and then only lose about 1/2 to 3/4 lbs of boost. Peak boost is usually around 19.5 psi and might drop to 18.8 - 18.9 psi at the big end of the track. There is no boost drop off in 1st or 2nd gears though. We are using an AFR 225 cylinder head and the 2.2L was all done in at 17-18 psi. We were overspinning it to get that and losing about 2-3 psi at the big end. The 2.8 can deliver so much more air, that this particular engine (at least with the hyd cam) cannot use so much as to have boost drop off even at 6,800 rpm. We were also using the lightest weight hyd lifters that were available at the time and the cam profile allowed for power to still be made (barely) at 6,800 rpm. The coolant hose that goes to the "in" side of the supercharger is fed off of the water pump. We are using a Mezier electric pump, and it has fittings for heater hoses. since we are not equipped with a heater core anymore, we use one of those to feed the supercharger. The outlet hose from the supercharger, feeds back into the front of the intake manifold, where the heater hose would normally have gone. We really had to slow the bigger supercharger down to get to the starting point of 18 psi compared to the 2.2L blower. The nice part of the bigger supercharger is that to get the same boost level as the 2.2L blower is the blower pulley is bigger, and gave more surface area of belt contact, so belt slippage went way down as well. We think some of the loss of boost was due to belt slippage and not due to the blower being a PD design. If you make a hard pass, or dyno pull and see any black dust on the blower pulley, you will also see a boost drop off. Also when we compare data logs, the boost drop off usually goes down as soon as a new belt is installed, verifying that it is really not all of the superchargers fault if there is a boost drop off at high rpm's.

We have a 'catch can" or oil breather/recirculater that is hooked up to the vent in the blower snout that captures oil vapor and condenses it and it goes back into the top of the blower drive case. I think this helps cut down on any oil being pulled into the case. So far every inspection of the screws has shown no oil contamination. When we pulled the supercharger off 2 weekends ago, the inside of the supercharger was as clean and dry as new. I forget what the 2.8 is rated at for rpm, but the 24K rpm I think is the limit. With the new cam ect, we are going to start with a 2.75" blower pulley and test from there. Data logging will tell the story. And if we give up a little down low, that is actually to our advantage in trying to launch the car on the small tire.

Thanks for the link, I go over to the corral on occasion and check the forums, but am not a member for whatever reason, time being the most likely. I think KB has tested the CFM of the superchargers, but is unwilling to disclose that info for one reason or another. The amount of testing and the thoroughness of the testing that Kenne Bell does is usually second to none. Maybe they do not think the average lay person has any use for information of that sort, or maybe it is a trade "secret" as they make their own supercharger cases as opposed to buying the base supercharger from Whipple like they used to do years age. Who knows. I do not have access to a supercharger dyno, so I guess it will remain an unknown for now. I have not been to Kenne Bell's website for quite some time, but at one point I thought they had a max HP supported rating for the supercharger sizes. I will have to check on that. It is kind of like getting Demon Carbs to admit to what the actual CFM flow was on a 750 carb, they would NEVER say. I was always told "it depends" whatever that means.

There is a lot more than just the supercharger or boost that makes HP as you well know. So from an airflow standpoint, maybe a 2.2L will support 750 HP, but you have to have everything else in order as well, and the typical street engine does not come close to having the hardware on board to make it possible, damn streetability issues always get in the way! That has lead this particular project more to being a drag only car. We still occasionally drive it on the street, but it is just crazy, when the boost hits your just asking for a ride to jail. The car was much more fun on the street when it had 450 RWHP and a 5 speed, Now it is either out of control, or lug it around like grandma when you take it out. Started reading your build thread at corral.net. DAMN. It takes a lot of perseverance to see a project like that through, especially when you are starting from scratch. I mean it is not like we can go out and buy a ready made kit and bolt it on. Good Job. There are a lot of people who would have thrown in the towel a long time ago.

92rohcp said:

My winter upgrade with larger sheetmetal race intercooler 3.5 in out pipe will reduce greatly that pressure drop and even with my bigger 205cnc TW heads going on and new cam the 2.8L should be there to furnish the boost level to 20psi with no boost drop off ip top.
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I would take a close look at your outlet manifold when you go to upgrade to the bigger piping. At some point the outlet manifold from the blower case to the piping is going to be a restriction. The stock outlet manifold does not have very much cc of volume. That could potentially be a choke point. Measure the depth from the outlet manifold face to the roof of the manifold and you will see that the air has to take a pretty sharp turn to get out.