Ok, here’s the sheet, but there’s a problem discovered today to which I’m going to have to redo the test as I have doubt it’s apples to apples. The reason for doubt? A few. 1, I was down about 45 HP from last pulls on this same dyno. I attributed it to DA as the other guys there were concerned they were down on power as well, but SAE correction factors should have taken that into account right? 2, in reviewing past logs in cooler weather I was making 1-2 lbs more of boost, again, I attributed that deficiency to DA. 3, my 60-130 pull this morning, DA was about 1500-2000 more then pulls made mid May -200 to +500 compared to 1700 this morning but the number was close 5.80’s before 5.80 today, but logs still low on boost. 4, the clincher, after the 60-130 run this morning I decided to try a 1/4 run, I’ve been holding back because of being parts breakage shy but time to get back on the horse so being bridge was clear I stopped and set up for a 1/4 run. Launched in usual street fashion, off idle and roll on the gas as the clutch was coming out and it fell on its face, blah literally, went to second blah fell on its face upon application of throttle, third same thing, I immediately thought TB issue. Got off next exit did a throttle relearn and adaptive reset and try again, blah. So home to go back to the BBK, throttle relearn, out on the road hit the gas blah on its face, no CEL no nothing. I thought ok, blower coupling issues again
. Well, it turns out it is a blower coupling issue of sorts but not at the couplings. Removed the blower belt and blower spins free and sounds fine, but clutch not working on the Litens. So remove TB and stuff a clean rag down it’s throat and lock up the rotors on it and grab the pulley and I can break it free from its shaft in the reverse direction but also can do such in the forward direction as well, ie the clutch is slipping, hence little to no boost. Soooo, I have to now wonder was I down on HP because I was down on boost because the pulley was slipping up top??? So was the pulley not slipping as much between the BBK 100 baseline pull and the 2 HHP 105 pulls??? Data was pretty consistent but I only did 1 BBK baseline pull, wish I would have given it another hit but I didn’t want to get allot of heat under the blower to heat it up when the engine was off swapping to the 105. So the data does appear to look like the bigger TB gained almost 20 HP and 10-13 ft lbs to TQ but for me to believe it I’m going to have to redo the test when a new pulley arrives, I gots ta know.
Now the decision is what pulley??? A Litens again? This would be Litens pulley #3, ie getting expensive as their not lasting since adding the +10 lower. Get a Satera heavy duty clutched pulley setup but their like 1200-1500 bucks last checked and no idea if their available off the shelf or not ie I can’t wait lol. Or 3, go to a grip tech 2.75 for 250$ and know no slip is going on
But a clutched pulley is much easier on the blower and all it’s drive gear, but more importantly a clutched pulley keeps boost up between shifts resulting in quicker times in everything from 1/4’s to roll racing. That was proven in development of the GT500 from things I’ve recently read on why they used a clutched pulley as well along with my own testing over the last 2+ years.
So here’s the dyno chart, and now the new question is- is the gain difference going to repeat with a new pulley???? Who says what this time??
RED graph is the BBK100
BLUE and GREEN the HHP105
Clearly a gain in both HP and TQ from about 4700 RPM and up. Pretty consistent both HHP105 pulls done one after the other, blue and green plots laid right over the top of one another, no cool down, just spool down, review, and repeat.
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