How much boost can I get on a stock engine NB8C
#25
At 12 psi you should never even shorten the life of the motor. After 12psi is when boost starts effecting the motor. How long it will last after that is a guessing game. How good is the tune, how often do you get on it, do you track it, street it, drag it. Aot of varibles.
As long as you don't have knock, or cylinder wash alot, your 12psi should be golden.
I'm pushing the envelope and going one psi over. Hahahha
As long as you don't have knock, or cylinder wash alot, your 12psi should be golden.
I'm pushing the envelope and going one psi over. Hahahha
#28
just FYI, 98 RON is roughly the same as 93 ( (RON+MON)/2) assuming a typical 'sensitivity' or difference of 10.
In theory and according to this handy-dandy graph which IIRC is from solomiata, you'd aim to run about a couple less psi of boost on a 9.5:1 engine vs a 9.0:1 engine to get the same dynamic compression
In theory and according to this handy-dandy graph which IIRC is from solomiata, you'd aim to run about a couple less psi of boost on a 9.5:1 engine vs a 9.0:1 engine to get the same dynamic compression
#29
And what about the NB fuel pump.....
Hi Jif, from all the world the answer comes from someone I know.... lol. Not sure why but your graph has gone, (or at least I can't see it). Luckily I donwloaded it before.
I have made 2 postings on this foum (to say thanks for the info everyone), they also had links to other forums articles but my posts have all disapeared so maybe they don't allow web links.
I think some people missed my real question being that the NB having a higher compression ratio than the NA is more prone to pre-ignition. And what power/boost people have managed on a stock engine. A few good answers though thanks, great to know 12 PSI is attainable without destruction (on a good tune).
I forgot to ask... are you guys with 12 (or more) PSI on the NB (Please NB only, as it's running higher fuel pressure and CR) still on the stock fuel pump? All the performance fuel pumps seem to just list the NA , does anyone know what the difference is? Can I just buy an NA one?
I have made 2 postings on this foum (to say thanks for the info everyone), they also had links to other forums articles but my posts have all disapeared so maybe they don't allow web links.
I think some people missed my real question being that the NB having a higher compression ratio than the NA is more prone to pre-ignition. And what power/boost people have managed on a stock engine. A few good answers though thanks, great to know 12 PSI is attainable without destruction (on a good tune).
I forgot to ask... are you guys with 12 (or more) PSI on the NB (Please NB only, as it's running higher fuel pressure and CR) still on the stock fuel pump? All the performance fuel pumps seem to just list the NA , does anyone know what the difference is? Can I just buy an NA one?
#30
Hi Jif, from all the world the answer comes from someone I know.... lol. Not sure why but your graph has gone, (or at least I can't see it). Luckily I donwloaded it before.
I have made 2 postings on this foum (to say thanks for the info everyone), they also had links to other forums articles but my posts have all disapeared so maybe they don't allow web links.
I think some people missed my real question being that the NB having a higher compression ratio than the NA is more prone to pre-ignition. And what power/boost people have managed on a stock engine. A few good answers though thanks, great to know 12 PSI is attainable without destruction (on a good tune).
I forgot to ask... are you guys with 12 (or more) PSI on the NB (Please NB only, as it's running higher fuel pressure and CR) still on the stock fuel pump? All the performance fuel pumps seem to just list the NA , does anyone know what the difference is? Can I just buy an NA one?
I have made 2 postings on this foum (to say thanks for the info everyone), they also had links to other forums articles but my posts have all disapeared so maybe they don't allow web links.
I think some people missed my real question being that the NB having a higher compression ratio than the NA is more prone to pre-ignition. And what power/boost people have managed on a stock engine. A few good answers though thanks, great to know 12 PSI is attainable without destruction (on a good tune).
I forgot to ask... are you guys with 12 (or more) PSI on the NB (Please NB only, as it's running higher fuel pressure and CR) still on the stock fuel pump? All the performance fuel pumps seem to just list the NA , does anyone know what the difference is? Can I just buy an NA one?
Also, looking at total boost is NOT the only thing to look at. Different turbo's produce different levels of HP at the same boost. It's better to look at HP than boost. 250 is rather safe with a good tune. Higher numbers have been done reliably. Paul, who posted in this thread, is making over 300whp on a stock 99' engine. I'm planing to make 350whp or more on a stock 99'. The trick isn't "how much boost". It's making sure everything is capable of supporting the power. And very good tuning.
#31
Thanks heaps PatsMX5, isn't the NB running 60PSI anyway? And what is the difference between the NA and NB fuel pump kit? all the Walbro kits I can find here in NZ just list them as for the NA. Will the NA one fit the NB??
You say a few have added an FPR, and blocked off the fuel return at the tank. I'm confused as I thought the NB is returnless. Where would the FPR be fitted?
And what is a sending unit? Do you mean fuel rail? I had mine out recently but it seemed to have some vacuume device mounted on the end so I did not modify it. Also any trick to un-attaching the wores from the back of the fuel rail?
Can you also explain the 1:1 vac/boost reference please?
Yes I agree HP is what it's all about, I was just interested about the effect of the higher compression ratio limiting boost. My target is 220RWHP. So I should be OK as long as I don't end up lean on my fuel supply. That's a beefy clutch and diff.
You say a few have added an FPR, and blocked off the fuel return at the tank. I'm confused as I thought the NB is returnless. Where would the FPR be fitted?
And what is a sending unit? Do you mean fuel rail? I had mine out recently but it seemed to have some vacuume device mounted on the end so I did not modify it. Also any trick to un-attaching the wores from the back of the fuel rail?
Can you also explain the 1:1 vac/boost reference please?
Yes I agree HP is what it's all about, I was just interested about the effect of the higher compression ratio limiting boost. My target is 220RWHP. So I should be OK as long as I don't end up lean on my fuel supply. That's a beefy clutch and diff.
#32
Thanks heaps PatsMX5, isn't the NB running 60PSI anyway? And what is the difference between the NA and NB fuel pump kit? all the Walbro kits I can find her in NZ just list them as for the NA. Will the NA one fit the NB??
You say a few have added an FPR, and blobked off the fuel return at the tank. I'm confused as I thought the NB is returnless. Where would the FPR be fitted?
Can you also explain the 1:1 vac/boost reference please?
Yes I agree HP is what it's all about, I was just interested about the effect of the higher compression ratio limiting boost. My target is 220. So I should be OK as long as I don't end up lean on my fuel supply.
You say a few have added an FPR, and blobked off the fuel return at the tank. I'm confused as I thought the NB is returnless. Where would the FPR be fitted?
Can you also explain the 1:1 vac/boost reference please?
Yes I agree HP is what it's all about, I was just interested about the effect of the higher compression ratio limiting boost. My target is 220. So I should be OK as long as I don't end up lean on my fuel supply.
99% sure NA and NB fuel pumps are all the same, even though all the kits are listed for NAs.
The regulator I bought to install one day has a 1:1 boost/vac reference. It has a little nipple that you hook a vacuum hose to and hook the hose to the intake manifold. Now it will change fuel pressure as to always maintain the same pressure difference between the fuel injectors and the intake. For example, on our "returnless" system where base pressure is always ~60, when we boost 15 PSI, we're now actually seeing a 45 PSI delta between the injectors and intake manifold. Loosing flow when we need it most. Definitely NOT ideal.
With mine I'll set it to idle at 70 PSI with the vac line unhooked, then hook up the vac line. Fuel pressure will drop to ~60 at idle, but when I go WOT, it will jump to 70 to maintain the 70 PSI delta. Then, when boost comes on, it will push fuel pressure up 1PSI per 1 PSI boost so that even when I'm running 20 PSI, I'll still have the 70 PSI delta. (70 base + 20 from 1:1 reference = 90 PSI). This is of course assuming the fuel pump is up to the task. Walbro 255HP will certainly be required for my setup and power goals.
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