125 MPH in the 1/4 - who's doing it and how?

[turbojimmy]

With the new Z06 trapping at 125 MPH, I'm thinking that's the new bar for my car. I know it's not an apples-to-apples comparison, the Vette does it on pump gas for gawd's sake, but I'd like to know what it would take to get my GN to that MPH. There are recipes out there and different combos in people's sigs, but I'm selfishly looking for specifically where I need to go (though my combo is similar to others' so it may benefit others).

I don't want to have to run stupid-high boost levels like I am now, and would prefer to keep the suspension close to stock so the car is still decent on the street. Right now my suspension is all stock (best 60' is a 1.57).

Specifically, what would I need to do different to get to a 125 MPH trap speed? Race fuel is obviously okay, I'm not terribly concerned with 'true' street trim but I want the keep the car 'streetable'.

Turbo? (I have a PT-61, 4" inlet, 2.5" out)
Fuel pump? (have a 340, I'm assuming I need more)
Stock fuel plumbing and rail okay?
Injectors? I have 60#
Heads? I have P&P stock heads
Intercooler? I have a CAS V4
Boost control? I have an HD actuator and a bleeder - is external wastegate required?
Headers?
Cam? Not sure what I have, but it's not stock
Engine management: when will stock no longer work? I have T+ and an LS1 MAF
Exhaust: I have a 3" THDP w/ 3" TorqueTech duals
Converter: I have a 9x11 3600 stall l/u (but it's not locking - need to fix that)

What else?

Jim

 

[SHADOWII]

:biggrin: Alchy!! :biggrin:

 

[Marc87GN]

With the new Z06 trapping at 125 MPH, I'm thinking that's the new bar for my car. I know it's not an apples-to-apples comparison, the Vette does it on pump gas for gawd's sake, but I'd like to know what it would take to get my GN to that MPH. There are recipes out there and different combos in people's sigs, but I'm selfishly looking for specifically where I need to go (though my combo is similar to others' so it may benefit others).

I don't want to have to run stupid-high boost levels like I am now, and would prefer to keep the suspension close to stock so the car is still decent on the street. Right now my suspension is all stock (best 60' is a 1.57).

Specifically, what would I need to do different to get to a 125 MPH trap speed? Race fuel is obviously okay, I'm not terribly concerned with 'true' street trim but I want the keep the car 'streetable'.

Turbo? (I have a PT-61, 4" inlet, 2.5" out)
Fuel pump? (have a 340, I'm assuming I need more)
Stock fuel plumbing and rail okay?
Injectors? I have 60#
Heads? I have P&P stock heads
Intercooler? I have a CAS V4
Boost control? I have an HD actuator and a bleeder - is external wastegate required?
Headers?
Cam? Not sure what I have, but it's not stock
Engine management: when will stock no longer work? I have T+ and an LS1 MAF
Exhaust: I have a 3" THDP w/ 3" TorqueTech duals
Converter: I have a 9x11 3600 stall l/u (but it's not locking - need to fix that)

What else?

Jim

I have not been near that fast in a GN so I won't even offer an opinion. I'm watching as well since we have a fairly similar setup. Anyway, as far as the lock-up, check for power at the purple wire going into the side of the trans for the lock-up solenoid. If there is no power, chances are, the brake switch(top one with vacuum line if you have cruise) is not allowing power through. My lock-up never worked and I removed the switch, disassembled it, made sure it had continuity when pushed in and went open when out. The lockup now works awesome and I'm cruising at 2200 rpms around 70-72 mph.

 

[turbojimmy]

:biggrin: Alchy!! :biggrin:

I've got that - didn't mention it though. Race gas is just much easier for me at the track. I use the alky on the street combined with 100 octane unleaded.

On the torque converter, it's not locking under a load. I can lock it manually under part-throttle, but at WOT it's slipping. It's either the converter itself or some kind of pressure problem in the trans. It would be nice if it locked because I'd get a little bit closer to that 125 MPH goal. I might take it out over the winter and have it looked at.

Thanks!

Jim

 

[TurboTnZ06]

I've only broke 125.00+ mph a handful of times. Usually run 122-124 mph. Same as what has been reported by some C6 Z06's. My site has all the mods and some pics too, enjoy. Btw, I saw a report that a test mule Z06 went 127 mph in the 1/4. Dayum. Stock they are puttin 440+ hp to the ground. With headers and no tune LG Motorsports put down 492 to the ground. That's gonna be a fast car. I'd say go for 130mph trap as a goal for your Buick. At least 70 mm turbo, heads, etc...

My Buick

 

[wants a tr]

see sig...

125 mph is moving mass for a 109 block car...

 

[Grandnat]

it can be done and it can be done on pump gas.... you don't need alky.


I have done it but it takes PARTS and tuning

my setup

Champion GN1 heads
71GTQ
F.A.S.T
CAS V2
212/212 hydraulic flat tappet cam
RJC power plate
stock headers
stock throttle body
accufab plenum
83# injectors
twin walbro 340s
TH400 w 4000 stall


with this setup I have done 6.68 @ 104.17mph with only 19 degrees of timing and 21 psi of boost. that was with a some race gas.


it only takes about 100 mph in the 1/8th to run 125mph in the 1/4 I have done 101 mph on STRAIGHT 93 octane and 18-19 psi.

 

[VadersV6]

Ive noticed a trend among alot of TR guys to avoid very high flowing heads. Dont know why. Thats where the power is at, and it doesnt harm streetability in any way at all like some think. The cam and intake manifold however, has everything to do with the shape of the powerband. The heads decide what numbers you end up with in that powerband. The reason the Z06's are making so much power, is flow. Those heads flow awesome, and they have a cam to match. The intake manifold has a runner length that is perfect for that curve. Unfortunately we cant really do anything with our tunnel ram style intakes. Dont ever get shy with the heads. If you want to tame down the idle and move the powerband around, change the cam.
If I had your goal and the money, I would get heads that flow even as much as 300cfm@ 28". There are plenty of street driving hot rods out there running flow numbers like that without forced induction. Alot of cobra guys are running ported heads that flow that much on a naturally aspirated 281, with total streetability. You add forced induction, and the power gains you saw in N/A form will be compounded drastically under boost. Get some really high flowing heads, slap in a cam with maybe 20 degrees more duration than stock, and a decent amount of lift but not alot of overlap. Add an alky injection kit, and you should be able to run those trap speeds on low boost with pump gas. Its all about the heads, and the turbo to match. With the wrong cam, you may lose 30hp, but with the wrong heads, you can lose 100hp. Same goes for the wrong turbo. But as far as the turbo goes, youve got that taken care of.

 

[JC Turbo]

I have a 9x11 3600 stall l/u (but it's not locking - need to fix that)

What else?

Jim

Jim,
I was recently have the same converter issues that you are having. I ordered a heavy duty lockup solenoid from Chris at CK Performance and it's been locking at WOT ever since.


John

 

[turbojimmy]

Jim,
I was recently have the same converter issues that you are having. I ordered a heavy duty lockup solenoid from Chris at CK Performance and it's been locking at WOT ever since.


John

I'll look into that - thanks.

As far as the rest of the posts go - thanks for the info! It's interesting to see how people are doing it.

When do I run out of fuel pump and/or injector? I see Grandnat has 83# injectors and twin 340s while TurboTnZ06 has 48# injectors and a single 340.

It sounds like heads are key. I have decently ported stock heads, but maybe a move to GN1s is in order. I need to start saving my pennies.

Jim

 

[TurboTnZ06]

It sounds like heads are key. I have decently ported stock heads, but maybe a move to GN1s is in order. I need to start saving my pennies.

Jim

And I only have bowl ported stock iron heads with stock sized valves. I just wanted the air to get around the valve nicely. The ports however, are untouched.

 

[turbojimmy]

And I only have bowl ported stock iron heads with stock sized valves. I just wanted the air to get around the valve nicely. The ports however, are untouched.

I have stock-sized valves with some bowl work and porting done, and the intake is ported to match the heads.

I just hate running 25+ PSI. If I can turn the boost down with better heads I think that's the way to go.

Jim

 

[bird]

see my post and/or my sig. 11.1@125+ pump gas. im running gn1's. i think they are a big contributor.

 

[victa1]

.....

 

[GNVYUS 1]

Its not going to be that hard with what you got Jimmy.
On pump it might be a tad harder but this will lock it for you easily.

Alky ( unless you run high oct all the time )
DOT's
70mm TB and Plenum with Power Plate. Good for 3 pounds of boost in backpressure.
Shave off some pounds, the Z06 is 3150, you might be 3550.

PM me if you want some weight savings ideas, I have all 309lbs documented with 25lbs coming off soon and only two mods I did not do, the fiber hood and trunk ( 65lbs ).

 

[turbojimmy]

Its not going to be that hard with what you got Jimmy.
On pump it might be a tad harder but this will lock it for you easily.

Alky ( unless you run high oct all the time )
DOT's
70mm TB and Plenum with Power Plate. Good for 3 pounds of boost in backpressure.
Shave off some pounds, the Z06 is 3150, you might be 3550.

PM me if you want some weight savings ideas, I have all 309lbs documented with 25lbs coming off soon and only two mods I did not do, the fiber hood and trunk ( 65lbs ).

Thanks for the info - I'll shoot you a PM.

How important is the TB and Plenum? I have a PTE 65MM plenum but not a matching TB. I also have the powerplate underneath it.

I have Mickey Thompson ET Radials - best DRs I've put on it. I didn't understand the DR hype (because I couldn't hook up with them) until I got the MTs.

Jim

 

[VadersV6]

I kinda wish the factory would have used a 62mm throttle body, given that the up-pipe is about 2 1/2 inches, and the flow suddenly hits a bottleneck with that tiny TB. 2.5"=63.5mm. A bigger TB would be a nice way to increase flow quite a bit.
People say, "Hey, stock TB's have run 10's!"....So what? Who cares? If you can go faster by increasing flow, which allows you to run lower boost levels, which allows you to run pump gas, WHY NOT? Just because a stock turbo has run 11's, doesnt mean you should keep running it. Just because you can push some stock part to the limit and run a fast ET with that part, doesnt mean that its a good idea.

Increase flow.
Lower your boost.
Run more timing.
Reduce heat.
Run pump gas.
Increase the life of your turbo.
Save head gaskets.

 

[sixgun86gn]

it can be done and it can be done on pump gas.... you don't need alky.


I have done it but it takes PARTS and tuning

my setup

Champion GN1 heads
71GTQ
F.A.S.T
CAS V2
212/212 hydraulic flat tappet cam
RJC power plate
stock headers
stock throttle body
accufab plenum
83# injectors
twin walbro 340s
TH400 w 4000 stall


with this setup I have done 6.68 @ 104.17mph with only 19 degrees of timing and 21 psi of boost. that was with a some race gas.


it only takes about 100 mph in the 1/8th to run 125mph in the 1/4 I have done 101 mph on STRAIGHT 93 octane and 18-19 psi.

He aint lying. I have come real close myself on straight pump gas with iron heads and a little 63 turbo.

 

[turbo2nr]

Don't be scared of boost. If it takes 30PSI, so what? If you can't afford to rip apart the motor and change heads, just blow denser air thru the same holes. That's how you go faster with a turbo car. Neat, huh?

 

[turbojimmy]

Don't be scared of boost. If it takes 30PSI, so what? If you can't afford to rip apart the motor and change heads, just blow denser air thru the same holes. That's how you go faster with a turbo car. Neat, huh?

I just like the idea of having room to grow. At 30 PSI I'd feel like I've got nowhere to go. Plus, my impression is that at that boost level there is very little room for error. A little knock and BLAM!

I'm definitely going to push the limits of this setup before I put heads on it. Based on the feedback here I may go for better heads once I feel like I've maxed out this combination (next year).

Thanks,
Jim