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I think he turns it 7400. He can't get to 129 with 4.56 and his current 26" tire.
So now you want a gear and tire change. Both of which will consume power.
Originally Posted by AINT SKEERED
129x4.56 -26" tire is 7600 rpm
129x4.56x28 is 7,058 rpm.
You want to cross at top of the rpm range
Lol! Yeah I picked 4.30 so I wouldn't be maxed out. If I got the math right I can get to 133 on a 26" tire. Then I will be maxed, BUT I'd need moar power to go faster, and I'm happy with getting comfortably into the tens and clearing 130 -- if it happens. Which it should.
Lol! Yeah I picked 4.30 so I wouldn't be maxed out. If I got the math right I can get to 133 on a 26" tire. Then I will be maxed, BUT I'd need moar power to go faster, and I'm happy with getting comfortably into the tens and clearing 130 -- if it happens. Which it should.
Thanks for a good answer without being a smart a$$.
I thought i read 28"tires in the past. I have read this whole thread but it's spread out and some of these threads run together. At 45 i don't remember every single detail i did at 25 .
Thanks for a good answer without being a smart a$$.
I thought i read 28"tires in the past. I have read this whole thread but it's spread out and some of these threads run together. At 45 i don't remember every single detail i did at 25 .
Lol. For sure, it's a long *** read. First trip to track was on ET street DR 28's. Second trip was on Hoosier QTP bias ply 26's. Def made it easier to hook and launch.
Read your build loads, love it.
Wish i was in states to get easier car parts, here in uk costs almost as much to post bits to here from US as buying the bits.
Except got jenvey 1 hr away...
Ever thought you might squeeze more out of yours with ITB's?
Regards
Gav
I actually have put serious thought into ITB -- the entire atmosphere becomes the intake plenum, so it's impossible to overscavenge, and there's no intake charge contamination between cylinders if/when air flows the wrong direction.
Right now, I've got a vacuum pump I need to get installed, and some other minor tuning tweaks, and I want to get it to the dyno. I'm hoping to clear 530, but we'll see. And with the block chipped, I'm going to wait until I don't have to tow it home from the dyno before I take it to the track and blow it up there - wrecking a LOT of people's nights.
Do you have any good links to your car vid wise or runs on track?
About yr or 18 months ago sent Tony M an email quizzing about build parts which still might be on the cards eventually, since then though interest rate dropped like a stone and cost me more than i expected to get on the road for kit car test, so money pit low atm. Also my clutch and slave are dead so another cost coming along soon. Got a quote for diamond stage 2 set up but delivery was almost $600.....tried myself to get cheaper but $500 to 600 would be delivery just for a clutch...bleedin customs on top....
Rant over
Regards
Gav
Bonus on the Vac pump.......Never understood the full magnitude of ring seal until I worked at a racing engine shop back in 2000-01....
Breaking engines in on the dyno and lugging them building heat (work) to force the compression rings into the fresh cross hatch. Then the Vac pumps being used in conjunction with multistage dry sump oil systems to pull crank case vacuum which prevents ring flutter....any time those compression rings can stay forcefully seated against the cylinder wall for a greater number of crankshaft degrees past top dead center......WELL that's more POP being captured....I jokingly call it "kicking the slugs"....in your case each GM Hyper is dealing with a considerable amount of insanity.....
Another update... Got the vacuum pump installed. It took more than it should have, but it's in and running. For those of you that just want to know how it does, AR Shale pretty much nailed it. SO, for the seat of the pants observations:
1. Idle is tamer. It's almost like the VP took 3-4 degrees of overlap out of the cam. I've got vids, but I need to compress them before uploading. It sounds like the old cam at idle. Which I'm fine with that. I don't need it to have the ShadyNasty idle. it just has it.
2. Cruising is better. I was able to bring my minimum cruising speed in sixth down a bit. I used to start getting shop around 1400-1500, now it's more like 1300. Doesn't seem like much, but that's 5 MPH.
3. More idle stuff -- The WB was reading richer. I run in open loop, and I had my idle at 15.3:1. Now it's 14.0:1 AND the idle speed is higher than it was with no changes to tune or TB. I think that the car needs less fuel at idle, and less air. I'm very interested to see if this ends up affecting MPG. One the one hand, I added a load to the motor, but on the other hand, the wind resistance under the pistons is less.
4. The important part -- Throttle response! The throttle response got noticeably better. I did some rolling hits in first and its completely useless. I did some rolling hits in second, but didn't film in case the car hooked, but it didn't. FWIW, it was 85 degrees out yesterday when I did this (Sonoran Desert FTL), so it's not like the pavement was hard and frozen.
5. The OTHER important part -- Power! It definitely gained. I've seen internet reports anywhere from 10-30 HP. I can't say for sure, but I'd guess it depends on bore size and what RPM you peak at as to how much you gain from a VP. Add to that, my rings were already sealing poorly, and I've got the crack in the block (but I don't think air is leaking in ), so it's really hard to make an educated guess. I'd be surprised if I only gained 10, but that has a lot to do with the big improvement to throttle response. I'm guessing it picked up 20-25 on the butt dyno. I'll find out for sure between trips (I travel almost every week right now for work)
Next post will have some pics of the install. It was a surprisingly difficult bolt on, but I think that has to do with the combination of parts I have already. I ended up having to modify the new brackets and reroute hoses, etc, to get the pump installed properly. Worth it for sure, but if you're thinking "Oh, I'll just bolt this thing on", you won't.
Wise man once said "Sometimes you have to mod your car in order to mod your car." This is one of those mods.
Before I get into this, a big shout out to 98_WS6_M6 for getting me the list of parts that worked for this installation. Saved me at least a week of returning parts and re-ordering stuff. Thanks, Mang!
Here is the belt routing, and you can see here how the mandrel is bolted on. There is room to move it another 1/4-3/8" closer, but that's it, unless you decide to try to run it off the serpentine belt.
Interference from the Intake manifold
Mocking up on a spare set of heads to figure out where to drill new hole.
I needed a new hole so I could trim the lower tab off the bracket.
Interference with water pump and tensioner. Note I had already trimmed this bracket once, and it was still interfering. I considered cutting the ears off the water pump, but figured it was better to cut up outside the car than inside the car, and I didn't want to remove the water pump
Interference with AC lines
Interference with fan shroud
Shoes a straight shot to the crank pulley after the clearance issues were resolved. The mandrel (not pictured) bolts right onto the ATI pulley, but you need to get three longer bolts
Darth I am assuming that you disconnected the PVC system from your throttle body, do you think that would account for some for the change in idle and idle fuel mixture?
Darth I am assuming that you disconnected the PVC system from your throttle body, do you think that would account for some for the change in idle and idle fuel mixture?
Had not thought of that... Very good point, my friend! The entire PCV is bypassed. If it was still hooked up, it'd probably pull air the other direction (from intake to crank case lol).
The first start vid is literally that. Started the car and started recording. The really high pitched whistling noise is the IAC. It always does it on cold start. Not VP related. Edit - in the video, it sounds like a really bad bearing, but it's the IAC whistling.
The warm idle vid is about 160 degrees. Enough to hear how it tamed the idle. It used to chop a lot harder at warm idle. it's actually touch quieter vs before too.
Last vid is the rolling hit into first. Not clutch dump, just part throttle in first and let her rip. it was 85 degrees out when I took the vid (Sonoran Desert FTL), so it's not like the pavement was super cold.
09-18-2017, 07:46 AM
