How many pounds of boost?

[pro69]

How many pounds of boost can a stock motor safely handle?

 

[Lee_Burough]

Limited by fuel

A stock 86-87 engine ran 13-14 pounds of boost with 93-94 octane available in the late 80's. At stock boost and 91 octane, you're limited to about that much boost. Put the fuel in that you wish to run, and monitor the knock retard with a scan tool....If it knocks, turn the boost down.

 

[Blazer406]

How many pounds of boost can a stock motor safely handle?

Define stock.

What octane fuel?

Alky injection can allow you to run mid 20's on boost fairly easily.

But Lee is right... all stock... pump gas.... 14 psi or so with a stock chip.

 

[Brer Rabbit]

Kentucky guys are running 30 #s

I bought some parts from a board member who told me they have made a bunch of runs at 30 #s of boost on a stock motor, I think at low 11 second e.t.s Tune the hell out of it and it should last at least 25-30 runs.

 

[pro69]

I'm not counting mods or gas,just mean the stock motor itself?

 

[pacecarta]

what year stock motor are you talking about
86-87 is a different motor than previous years.

 

[pacecarta]

the motor is not the limiting factor , the fuel and the tune is!
run with knock and you can pop a gasket or worse

with stock chip 93 octane 13-14 psi is about it
on a hot day maybe less

get a knock monitor like scanmaster and then tune for no knock
get a better chip with lower timing 15-17
get a better intercooler and add adjust fueling maybe 20
get alky injection which is an octane improver and a chemical intercooler and a fuel and mid 20s and mor can be tuned in if your fuel system (pump injectors) are up to the task

a stock motor with a stock turbo went 11.40s at 25 or so psi on alky injection , now it had some supporting bolt ons to improve airflow but the motor itself was stock, others have reached 10s with bigger turbo .

 

[Renthorin]

I have heard "if you are not knocking there is no limit". I take that to mean boost doesn't hurt the motor knock does and we all know this but I think what he is asking is at 57.3 pounds of boost (random number), even if you are not knocking, will something just pop from the pressure?

 

[Turbo1dr]

This question is the same as asking "How many licks does it take to get to the center of a tootsie roll pop." You guys remember that question? It took Mr Owl three licks and then he crunched it!

 

[Blazer406]

This question is the same as asking "How many licks does it take to get to the center of a tootsie roll pop." You guys remember that question? It took Mr Owl three licks and then he crunched it!

ROFL .....

 

[pro69]

I was refering to 86-87's.I should say that if you have the right and supporting mods to a stock motor,what boost can the stock motor handle.
If you can't tell,I'm a newbie and have a lot to learn,that's why I'm asking.Thanks for the replies.

 

[Turbo1dr]

Actually, the amount of boost for a stock unopened factory engine can be very high. This is because the amount of boost isn't getting into the cylinders as good as an engine with ported heads, intake, larger valves, better intercooler...etc. There is a point of no return when the engine doesn't make more HP with more boost. This is the reason why you can run 35psi of boost and only get into the 10's with an unopened engine. You can run much lower boost on a modded...ported heads/intake...larger turbo...larger intercooler set-up and run faster. Just remember 500HP with 30psi of boost is the same as 500HP with 20psi...it's all in how much you want to spend for upgrades.

 

[BlackBandit]

Actually, the amount of boost for a stock unopened factory engine can be very high. This is because the amount of boost isn't getting into the cylinders as good as an engine with ported heads, intake, larger valves, better intercooler...etc. There is a point of no return when the engine doesn't make more HP with more boost. This is the reason why you can run 35psi of boost and only get into the 10's with an unopened engine. You can run much lower boost on a modded...ported heads/intake...larger turbo...larger intercooler set-up and run faster. Just remember 500HP with 30psi of boost is the same as 500HP with 20psi...it's all in how much you want to spend for upgrades.

Exactly! Assuming the tune is correct the amount of boost doesn't really matter. The bottom line is that it takes a certain amount of air and fuel to make x amount of cylinder pressure/horsepower. Now, if x amount of HP is more than the internals can handle, then when you achieve that the engine will fail. Doesn't matter if it's running 35 psi with a stock turbo or 20 psi with a 70 and ported heads. HTH james

 

[pro69]

Ok,thanks..........that makes sense.
So then how much HP can a stock motor safely handle?

 

[pacecarta]

safe is relative, no increase of power without watching tune closely is safe , but watch the tune and feed its needs with supporting upgrades and the stock motor can handle more than the stock heads will allow to flow in and has been proven to be fairly reliable at that level .

port the heads add a cam and low 10s are possible but is it safe as in is it reliable enough to do this day in day out , NO . most would agree that when aiming for 10s (500+ RWHP) the bottom end should be addressed with at least main caps or a girdle , low 10s on stock bottom is like rolling the dice on every pass , feels good though , so far mine has done ~620RWHP

and at the level the stock motor can take you on the track youll need a roll bar for safety as well upgrades to trans, axles and driveshaft as those are a more common failure (many have done without these but is it safe or wise , i'd say NO )

 

[yullose]

So what are you buying now Adam ?

You know Jim and I have put both our cars into the 10's on stock motors right ?
We both run 25-27psi boost.

It's not hard at all to get these cars into the low-11's / high-10's on stock engines. You just 'gotta know what parts to buy...

 

[87geeinn]

I shoot for 78-79psi.

 

[Blazer406]

I shoot for 78-79psi.

Why so low?:biggrin:

 

[Quick6'n'-K.C.]

I bought some parts from a board member who told me they have made a bunch of runs at 30 #s of boost on a stock motor, I think at low 11 second e.t.s Tune the hell out of it and it should last at least 25-30 runs.

I have over 150 passes at 32psi + and never blew a gasket or the motor. EDIT TE44 AND 50 NOT ON MY WHITE CAR

It was plenty rich and the car loved it

5 years later and its my daily driver with the same setup minus turbo, ic and injectors.

I thought i would chime in and say, that running 30 psi with most aftermarket turbos and lower timing will get you low 11s on a stock long block.
Might even go faster.



pro69- Its not what a stock 86-87 buick motor can handle, cause at 15psi and alot of timing on a race chip with pump gas will surely blow the motor up.

I think you need to make sure that your car has the correct setup before you try and beat on it.
Even a agressive chip on pump gas will eventually blow it up.

HTH

BW

 

[1NASTY69Z]

Adam,Ive had my car as high as 28lbs.Ask Greg how it runs,I let him drive it Did you go and look at that GN??