Che70velle

iTrader: (6)

Well said sir.

Che70velle

iTrader: (6)

So I drove the car today, after messing with my off idle tuning some. The car, which is a pro-touring 70’ Chevelle with a custom chassis on coil overs, built by myself, is running Falken Azenis 615k tires, which are sticky. They are however a summer tire. It was, for the record, 61 degrees here today, so not exactly hot, but not too cold either.
My first impression is perhaps I’ve messed up? I was expecting the car to be strong. I’ve watched countless videos of Tony’s combos in corvettes over on Corvette Forum, running 1/4 miles, 1/2 miles, street runs, etc. They are fun to watch, due to the shear power these combos make. I expected similar results.
What I did not expect was the car to spin in 4th gear effortlessly. I never got to full throttle.
After my first mile trip, I came home thinking that my clutch is slipping badly. Up on the lift to check everything, and it all looks great. So back out I go, and I got out about a mile from the house on a long straightway, I roll into the throttle about 3/4 and it violently explodes into wheelspin. At like 55mph. I’m in 4th gear just cruising.
Dry roads. Geesh...what have I done guys?
My Texas Drivetrain Performance stage 3 clutch is rated at 750 torque.
I still have more tuning to do. The car idles beautifully, but has the infamous low speed surge, which I’m determined to make go away.
I can’t wait to get this stupid thing on a dyno....it’s stout.

Darth_V8r

iTrader: (4)

Oh I'm sure you've got an animal on your hand now. Warmer pavement will help but you may end up taking either some timing or fuel out at lower rpm and part throttle just to detorque it some for DD. I had to do that myself.

blk00ss

iTrader: (66)

A set of 15x10’s and some 275 pros will take care of all that spinning crap.

lowcountry

iTrader: (1)

Well $hit. Thanks for the warning - getting mine ready for the first outing.


Just got a start up tune. Next up a trip to Kooks to have the exhaust installed.

NAVYBLUE210

Congrats on your progress. I just reviewed your Build specs here
and Your hoped for goals on your Lateral G Thread as well. Don't
Remember if you have a vacuum pump installed or planned
But with one I would bet on 650+ RWHP with your solid roller
Cam specs, Compression, Quench and attention to details.
Really curious to see your Dyno Graph & results to see if
The MSD can peak at or above 7000 RPM.

NAVYBLUE210

Help Yes, "take care of ALL that spinning crap"
NO
LOL!

Che70velle

iTrader: (6)

Thanks Navy. I don’t have a pump, but I’ve looked into it. How much power is a pump worth?

NAVYBLUE210

It has been reported here on Tech 12-20 RWHP with
12-15" of Vacuum. Some suggest no more than 12"
On a street system. Ring seal is huge, I would look
at the GZ system and search the Dyno results section.

Darth_V8r

iTrader: (4)

I dont think there's a definite solid answer here. I think the improvement gets better with displacement because you gotta displace the same air above and below the pistons. I also think the improvement, er..., improves with rpm. Again you gotta displace more air below the pistons as rpm increases.

I do think I picked up a mpg from reduced pumping losses even for daily driving. Definitely improved on the freeway.

All that to say I can't give you a definite number but it's enough I noticed it.

Che70velle

iTrader: (6)

Yeah, I’ve read that about the vacuum numbers as well. 12-20 at the tire? Wow.
I’ll look a little deeper I guess.
Thanks man.

G Atsma

WOW. I never would have guessed a vacuum pump to add that much to the ground. I KEEP learning here.....

gnx7

iTrader: (28)

Engine bay looks good!

Unless you have an R compound out back (100 tread wear) you will have a hard time hooking up that power is my guess.
Nitto NT01- great streetable performance tire with awesome grip once warmed up

https://www.nittotire.com/competitio...d-course-tire/

Tony @ Mamo Motorsports

That's a bit optimistic honestly at engine crankcase vacuum levels safe to run on the street (8-10" of vacuum or so).

Note you can run a little more vacuum if your running piston squirters to keep the wrist pins lubricated but most builds don't include them. Also the larger gains from a vacuum pump upgrade assume an engine is built with a vacuum pump in mind....something with light tension thin rings etc. On a stock engine with standard tension rings there are less gains to be had with this mod especially at reasonable amounts of crankcase vacuum (like I mentioned earlier 8-10"). You may only see 5-8 RWHP with an OEM or more conventional build but that's still better than a poke in the eye!! (Going from what is typically low levels of crankcase pressure to a vacuum environment makes it a little easier to spin up that rotating assy!)

Even engines built for the pump....at 10-12" of vacuum assuming your rings seal up reasonably well you might bump the output say 10-14 RWHP but when you consider how hard it is to find that type of power at that level its certainly an upgrade worth considering if your building an engine from scratch and can install custom pistons with thin rings, lateral gas porting, etc. to take full advantage of the upgrade.

Hope this helps guys



Regards,
Tony

Darth_V8r

iTrader: (4)

That is helpful. On mine, I sort of guessed at the gains based on the ol' reliable butt dyno, but what I noticed more than raw gains was the increased "snappiness" of the throttle response as well as some taming of the idle.

Che70velle

iTrader: (6)

It’s been a little while guys. Biggest gremlin here in N. Ga. is rain. It’s been a very wet winter here, so not an awful lot of driving so far, in fact only been 45ish miles. Car runs great, but I have oil on my plugs. Yup. I either have an oil ring issue, or the 75 lbs of fuel I had, which was the cause of my initial surging I was experiencing, washed the cylinders down and hurt the rings. It’s a shame really, as I said the car runs strong. Changed oil a couple times, and inside of oil filter looks good. Had a warm dry day to tune/drive it, and the car did hook ok on a roll, so no more 4th gear spinning, but it ate my clutch...
So I picked up an RPS BC2 clutch, and I’ve got head gaskets coming from Tony. I keep ring sets on the shelf, so I’m going back in. Not what I wanted to do, but I’m a big boy, and I have to pull the combo out to change the clutch anyway. Pulling the engine down to change rings will take a few extra days, IF I don’t need a hone.
Gotta get it right at this point. I won’t settle for anything less. Spring/summer is coming fast, and I want to have the car perfect for nice weather.
In hindsight, I’m glad the dyno day didn’t work out for me yet, as I would have lost the clutch on a pull, and wasted my money there. It’s all good. That’s hot rodding. I’ll keep you guys posted.

G Atsma

Best of luck Scott! Hope you get it all sorted out! And yeah.... that's hot rodding!

lowcountry

iTrader: (1)

That sucks. I hate oil where it ain't supposed to be...


How did you blow your Clutch? What brand was it? I installed an RPS in mine. Have no experience with them, but for what they cost, I'm hoping it will be bullet proof. I have no desire to replace my clutch anytime soon. With the way the DSE sub frame sets the engine back, I'll have to pull the engine to get to the clutch...


Good luck.

Che70velle

iTrader: (6)

Clutch let go in a hard 3rd gear pull. Weather was warm, and tires hooked well. I thought it was tire spin for a second, but it made a grinding noise as revs came up. I lifted and got right back in, and realized that it was my clutch. Thankfully I haven’t been very far from home yet, and I limped it home. The clutch was a TDP (Diamond) stage 3, with about 1500 miles on it. RIP...

I’m starting the 6 liter install tomorrow that I’ve just finished, in my nephews Silverado, so it will be next week before I get to pull mine out.
The engine in my Chevelle is 3/8”’s off the firewall, so like you, it all has to come out to separate the transmission from the engine. From a maintanance standpoint, it stinks, but from a performance standpoint, which is what the entire car is centered around, it makes sense to move it back.
RPS this time. I laugh at myself thinking about not going this route originally.

lowcountry

iTrader: (1)

So, I have a dumb question. How do you know the oil is getting by the rings and not something else like a pcv issue?