Wicked69

Okay, let's hear what you all think....and of course I will try to prove everyone wrong. (With some help of course)

My 3870lb Chevelle with Stock 5.3, Twin PTE62/62's, 20lbs of boost, E85, and water/meth injection, TH400, 3.90's. 28" tall tire, PTC 3400 Convertor ran a best of 118mph, 1.50 60ft, and 6.31.

Now, I have another 5.3 but have twin On3 70mm turbo's with a .68 AR. My PTE62's had a .58 AR. I am also going to change the rear gear to 3.08 or 3.42, same cam, same fuel and some better tuning I think I can get this car in the high 5's at the same boost. He says "No-Way" He says turbos are way too big and my gears will be way too tall. I also will be running a 30" tall tire (315/60 vs a 275/60....

So, I have to keep the same cam, use a 5.3, these turbo's, no convertor tweaking, and one of the above mentioned gears. What do you all think? And Why? I know Skinnies and Denmah have said no in another thread but why?

I think if I advance my cam, use the 3.08's or 3.42's, race on E85 with the more water and less methanol injection and a little more agressive tune that I can reach it. Let's hear your opinions.

LS1NOVA

iTrader: (12)

Id say with a two step, transbrake, and traction, yes.

Without, no.

IMO.

FasTimeSS

iTrader: (47)

theres ur first problem taking advice from denmah

71 chevy

iTrader: (18)

here is the thing, your buddy is right, but wrong at the same time.

the new turbos are bigger so will spool slower. he is right there. but if you are leaving of a tbrake, that combo will run the same time as it did before because you are in a similar efficiency area of both turbo maps.

where he is wrong is, you already ran 118mph. in a well setup combo, that would be a 5 second pass. the area of opportunity for you will definitely be in the 60ft. it needs to be in the low 1.30s

to get there, you have to leave on more boost, and a higher rpm. what boost and rpms are you leaving on right now?

again, this is what i like to use to see a combos potential

http://www.rehermorrison.com/PdfFile...eriesHP_ET.pdf

427

iTrader: (3)

Might work. Leave one of the 70mm turbos home and shift at 5200-5500rpm.


Kurt

denmah

iTrader: (2)

FasTimeSS

iTrader: (47)

love ur sig man your my hero

Wicked69

Keep in mind, I had only tuned the car a couple of times. It was still a very basic and conservative tune. Running very fat and very, very, low timing. So I don't think the other set up was ever even closed to maxed, I just made the mistake of trying from 20lbs-23lbs of boost at the track between passes. Got impatient!

I am going to try to use more timing and less boost now.....

LilJohn

Super fat and no timing..... good way of burning the exhaust valves right outta the motor.

28 degrees outta boost. 16 degrees at full boost. Start at 12-15 psi. Target .74-.75 lambda. Wait till 5-6 psi to pull any timing at all.

READ THE PLUGS. Do wot shut downs and pull em. Get the fuel right...then walk the timing in while watching the fuel. Your target air fuel could get as lean as .78... as rich as .72. Mph will tell you whats best. 18-20 degrees shouldnt be out of the realm possibility for you.

Read the plugs. Read the plugs. Read the plugs. Watch the mph. Listen to what the motor tells you. Shes just like a woman.... she will make her wants and needs known....if you can understand how shes gonna tell ya.

Wicked69

That's good info. I actually said "low timing" though. I was 28 degrees out of boost and 12 at full boost. I pretty much had it tuned to idle and WoT. At idle I had an AFR in the 14-15 range on a gas scale and 10.5-11.1 at WOT. I did read my plugs. The car ran so well I just didn't want to tune everyday, so I ran it for a couple months and then I pulled some timing on the transbrake and leaned out the VE table and added a little at full boost. Again, the car ran well so I left it alone for a few months while I messed with the meth injection and figuring out when to have it kick on and how much methanol to add. etc... I was always checking my plugs. The engine lasted 7 months and the only reason it blew was because I finally got impatient and up'd the boost from 20lbs to 23lbs but I only had a 2 bar tune, so guessing anything above that. yeah I know that was the stupid part.

I have the engine in the garage now. What is interesting is the #3, 4 cylinders are missing the pistons and the rods. All the other pistons and rods looked fine. Even the rods are still connnected to the crank in 3 & 4 by the arp rod bolts but the rods had "twisted" off.

I plan to do as you an 71 chevy had mentioned and focus more on the timing this time and use less boost instead of less timing and more boost.

WheelsUp84z

iTrader: (14)

you're pretty brave to go even to 20lbs on a 2 bar map.

T76s10

iTrader: (6)

i think you can make it work. theirs a mustang with twin 70's on a 5.3 and hauls. plus, the on3's 65mm turbine housing will help you spool

skinnies

iTrader: (33)

Not suuuuper fat, but we've been fat on the tune and low low timing(pulling for traction, I'm talking down to sub 5 degrees) and NEVER hurt an exhaust valve in a ls JY setup in the 800rwhp range(before timing being yanked of course). Ideal nope, but neither was our racing conditions, but we've never hurt anything doing this on several setups.

I still think the 62's was a better combo. As far as pulling gear I don't think it will hurt you IF you can control power and make it work.

WheelsUp84z

iTrader: (14)

I think switching to lower gears, thus reducing the mechanical advantage, will help improve your times... thats provided everything else is set up correctly. Will allow you to leave on a little more boost/power without overpower the tires (as easily)

I8UR4RD

iTrader: (16)

focus on the 60 foot and make a 100lb weight loss goal

71 chevy

iTrader: (18)

if this is true, PLEASE man get a 3 bar.

Sarg

iTrader: (6)

Think I would do the 3.42 gear and see how that goes. I think if you get the tune right on the trans brake you should be able to get that 5.3 to spool those 70s. Those 70mm on3 units after all DO have a kinda small turbine wheel. We have one almost finished up on a 5.3 with twin on3 70s. Depending on how it acts we are going to some BW units later, but figured we would get the set up started on the much cheaper on3 units (1/2 the cost on the turbos). Keep it lean on the 2 step and it should come up on boost.


And like 71 chevy said, please get a 3bar! It is not expensive.

T76s10

iTrader: (6)

Doesnt a 3 bar tune need a 3 bar map also?

Sarg

iTrader: (6)

yes 3 bar map sensor is not that expensive.