psi doesnt mean poop since it varies in every setup. actual flow makes the difference. Youre motor has its limits since you can only hold so much cylinder pressure with your setup. around 800-900 is were youre limited to without running chances or being on the edge of pushing water.
what are actual specs of cam? at 14 psi from a 76mm turbo on a 6litre should be well into the 700-750 rwhp range
one thing youll have to keep eye out for is IATs if youre iats are thru the roof then youre going to be limited to amount of power you can push.
3" for 3 feet, then 3.5" the rest of the way. I mean i’ve seen lots of setups run 3" the entire way back and be fine. Not saying it may not be the problem but that would suprise me.
They did give me the spring rate, but I forgot i’ll have to send them an email. They said the spring pressure was borderline for a N/A setup, but with the boost its terrible.
I only had 6k on it with the old cam, it musta been really hard on those damn springs…
I can’t find exactly what spring pressures of the springs atleast what they were supposed to be. I know they are dual springs.
Try to find out. An aggressive cam lobe will wear down springs after a certain amount of time. Its not uncommon to have to change springs every 6-10K miles depending on the lobe. Some can make it longer but you would see power drop off.
ive seen setups push 15 psi from a Pt88 on stock springs, something to think about
What was the cam used and what rpm? You maybeale to get away with stock springs on a stock cam with boost. Spring rates will vary with cam lobes and valvetrain mass. Boost may require more spring rate and seat pressure to control a lobe over a n/a setup, but its the rpm range and cam lobe design that really determines what springs are needed for any application.
Hmm, I may have changed my mind about upping the boost… I just took it for a spin its retarded fast as it is. I still have a lot to finish up though, the interior is in shambles tach isn’t working. Notice a small oil leak from the return line a ton of little stuff I really dont want to do.
setup im taling about was stock cam and stock rpms range.
Dual springs should be changed every 10-15k miles if used with an aggressive cam or alot of boost pressure
AR will also effect back pressure a 81 would make sense for your high torque number and lack of HP, if you can measure back pressure preturbo it would tell you if that is your issue. .96 will deffently help carry further out, sharp bends in the exhaust will also hurt some but probably not enough in your case.
what are specs on cam?
you can encounter valve float if you have to much back pressure, your cam along with small AR can be hurting you. Some say overlap is bad but to much neg over lap will shorten your RPM range. I prefer some overlap since it carries alittle better. Makes nicer for topend power
140 is pretty healthy and I’m abit surprised its seeing float as early as 4K rpm. Thats an XE-R lobe which are known to be pretty aggressive on and off the seat even with modest lift. Whats probably happening is combination of too little spring and maybe some backpressure. Cam is setting the valve down way too hard on the seat and its bouncing.
You need a good double spring with probably closer to 160-180 lbs on the seat. You can get patriot x-treme gold springs, or AFR 8019 springs, or similar double springs and shim them about .03". They are good to .650 at normal install height of 1.800" so with shimmed to 1.77 or so, you get 165 or so lbs on the seat, with good lift to .620 which leaves plenty of margin with that cam. You could even go more with another .015" of shim and have more pressure to ensure the valve stays down on the seat.
Also get titanium valve spring retainers if not already have them. Those do help alot.
With springs alone, you should see well near 650whp on same boost since you will beable to rev out to over 6000 rpm.
No race gas? Fine… go E85!!! I’m running E85 and just over 600rwhp NA with a stock 85mm MAF and stock Ti catback on my car. Speed Density with an better exhaust and it might have 620+ in it. With boost E85 will help you even more. And with all the motor and plumbing in such a small space the cooling effect will be huge for you as well. Seriously, I thought somebody said there were pumps in your area, you should think about it. And you said the fuel system can handle all you can throw at it, so hopefully you won’t have to make changes there (figure you need roughly 30% more fuel). If you’re over 60% duty-cycle on injectors now you’ll want to bump those up. FWIW I’m running 80# injectors to support my 600rwhp, but I’m actually really low duty cycle (which I like) eve on the E85.
Please… race gas in any car you drive on the street is absolutely stupid. Same with E85, its different for cars that are E85 compatible that mix, but if I have to have it to be able to get on it safely its also stupid. I’m not sure people understand the definition of a street car.
I want to be able to drive this thing anywhere, no matter where I go and not worry about being able to find E85 or race gas.
FWIW, we usually like to see about 165 on the seat for turbo motors. The AR of the housing plays a role as well. Too much exhaust back pressure compounds valve spring problems. The springs in it now may be just fine with a .96 AR. Hard to know, hard to tell. All you can do is crunch the numbers, figure out what’s NEEDED, then go from there.
Yeah, i’m going to fix them eventually… haha. In a completely unrelated issue to anything i’ve done with my car since I bought it, my seals on my PS rack when out. So I have to fix that first.
Yep, It’s strange as hell. Was fine no leaks all of last summer, pull in the garage for the winter. Take it for a test drive; down to VA. Started to get a slow leak in VA. Now it will empty the all the PS fluid within an hour of filling it, even when the car is off. I’m just lacking motivation to work on the car, I havent touched it all weekend. I had a big party saturday and was hungover all day sunday… then had to change the brake master in my dads truck.
I might pull it today… and then decide if I want to keep the PS or convert the rack to manual. There’s a good write up on what to take out and weld to actually convert it… not just loop the lines. I’m hesistant to do it though in a street car. I guess if I have to buy a new rack it might be worth it just to try and see how I like it.
I guess I’m “stupid” then. I still haven’t found another 600+ rwhp NA street driven (easily daily drivable, I just happen to have other cars) LSX. I’m really not sure how my car is not a street car. I drive it to/from the track (some are a full day’s drive away). I take it to work a lot. I drive it for fun up in the hills on the weekend. I’m not sure YOU understand the definition of a street car. I’m pretty sure it’s a car that’s driven on the street, hahaha. I just keep a 91 octane tune handy in case I need it. It’s that simple. Don’t get all hurt just because I’m making more power NA than you are w/ the turbo.
No, you don’t need E85 or anything to go over 600rwhp on a turbo LSX. At least you shouldn’t. But it’s basically free power so why not? Most turbo guys see around 10% more power on E85, it runs waaaaaaaaaay cooler (which I think would be a big benefit in this car), it basically doesn’t detonate but just stops making power if the tune is off, it keeps the motor cleaner, and it’s cheaper than 87 octane. Why the hell not use it? Like I said, just keep a 91 tune handy and then you’re fine.
I wish it was readily available here…I would love to try it, but we only have three stations in the whole Pgh area that I know of and none are close to me.
