How much Boost on Stock Internals?
 

Hello guys, thanks for the help with the "Not Holding Boost". It turned out it was bad ignition wires. Got hot, and got bad. Anyway, I have an open air filter and a 3" exhaust from my downpipe back. I also have an NPR intercooler. I am about to put in a boost controller and was wondering what is the highest amount of boos I can push on that set up? Also, I will be installing a 2mm MHG soon after. What about then?

Probly a decent 12-14psi
But be sure the engine is running healthy
Beyond any doubt b4 boosting the car

A new fuel pump, and an afc to control it should be your next mods in the list

What's an AFC? I was thinking about putting in a VPC and GCC with a set of 580cc injectors, but not for another few months.

Have you heard of fuel cut?

Yea, I was also gioing to get a fuel cut defenser from HKS. Is that good?

fuel cutoff is like 10-14 psi

http://www.suprastore.com/19turspec.html

Horsepower 230

Torque 245

Weight 3400-3500

Engine 7M-GTE 2954cc

Transmission R154

Boost 6.8psi

Turbo Toyota CT-26

Spark Plugs NGK BCPR6EP-N8

Injector Size 440cc

Compression 8.4:1

Cylinder Pressure 142

Fuel Pressure 33-40psi

Fuel Shutoff 11.4-13.7psi

Intercooler Efficiency 3psi drop@6.8psi

Wheels 16x7 / 225-50-16

So that means that between 10-14 psi, the fuel will cut out? Why at that point? Is it some kind of protection?

Fuel cut is when the fuel pump can no longer flow enough fuel to supply what the injectors are demanding. Fuel pressure rises about 1 psi for every psi of boost. As fuel pressure rises, flow falls. Yes, I know that doesn't make sense but it is a proven fact. That 10-14psi range is just the general range that a stock fuel pumps' flow falls off. Now when that happens the air/fuel ratio becomes dangerously high and detonation is emminent. Thats when the ECU cuts the fuel entirely to prevent damage. You can raise the fuel cut boost range with mods like a walbro fuel pump, 550cc injectors and a lexus MAF but fuel cut will always be there. It's your engine's way of telling you you need more fuel.

okay..So do I have to use the Lexus AFM, or will the VPC be good enough? I will be using it in conjunction with a GCC anyway.

i was boostin a steady 12 without hitting any fuel cut

but then my bov broke, and the car was overboostin nut still
i was boostin a steady 10 until my bov got worst
never hit fuel cut

get an afc, a new pump, you can still stretch out the injectors

im sure nate knows what he is talking about

I don't think he was being an ass
Jus another question in the forum,

Plus 667rwhp says he knows what he's talking about lol

http://i113.photobucket.com/albums/n...uprafest-1.jpg

http://i113.photobucket.com/albums/n...supra027-1.jpg


dyno sheet and proof

a very delightful discussion here

stock ct26 is good to 13-14psi, after that its just a hair dryer. ive heard that fcd isnt any good but thats just what ive heard.

I say > listen to Nate..he knows what is going on. He has a way or telling people how it is and that is what people like about him. LOL

Duane

i felt the fuel Cut tonight in long beac CA
 

Damn nate i felt that Fuel Cut i was with my lil cousin and two friends and i bought my 88T Targa top supra on sat and i took it for a nice spin today and floord it and after i stopped the whole car shut off and the check engine light came on...if thats wha u mean by fuel cut...buh can i ask u a question also...wen i turn my steering wheel all the way it makes a knocking sound badly..i can use ur help PLZ im new this dis...TY

hey whats the best injector brand to go with

This is incorrect!! Fuel cut is the ECU slowing the fuel injectors to idle, To stop the car from breaking itself. It stops it when the AFM is reading higher than a predetermined frequency. That is why its a general range, because of air temp, humidity, barometric pressure, etc. It is not the fuel pump failing. If you hit fuel cut it feels like you just broke something, and the CEL will come on for a little while. And detonation happens because the inside of the motor is getting so hot when the piston is on the way up it detonates the fuel before the sparkplug does, also not because of fuel. It can detonate because of lean air/fuel, but thats not all that causes it. And not matter how much gas you have, the ecu will still cut it just the same. Its about air! not fuel. But of course they must match. All the lex afm does is let unmetered air go through, and the 550s to make up for it. which is basically a crap shoot with tuning.

You guys sound like you know enough, but there is no need ot fight. I don't have much to spend on this car right now, therefore, when I do something, I like to do it right the first time and not half step. If I use the HKS VPC as an afc, will that be sufficient? Like I said, I don't want to buy something now and in a about a year, by the thing I should have bought when I do my rebuild.

First of all AFM's run on voltage not frequency, its not a motherboard cpu. Ever read live data from a scan tool?

Guess what happens when there is not enough fuel? Detonation. Air is plentyful, you will never run out of air on a motor. It's fuel you will run out of. Which causes the Air Fuel ratio to spike, causing detonation. All of this happens faster than you can blink your eye.

"And detonation happens because the inside of the motor is getting so hot when the piston is on the way up it detonates the fuel before the sparkplug does"

Nope, thats preignition. Detonation is an explosion inside the cylinder no matter what stroke the piston is on and it usually results in a hole in your cylinder block. I've seen it before.

"also not because of fuel"- No, its because of lack of fuel that the stock fuel pump can not deliver.

"It is not the fuel pump failing."

Never said that, please quote me where I stated that.

This is where you said the fuel pumps fails. Not fails at life, but fails its job. The fuel pump can flow more than enough for the stock injectors. The ECU causes fuel cut, its a safety feature. It doesnt "just happen"

Turbo AFMs produce a frequency. Thats how the ECU knows how much air is going by. And detonation is when the air/fuel is ignited by a source other than the spark plug, Mr technical. And it does not blow a hole in your cylinder, it makes a knocking or pinging sound. ANd no, Im not denying that it can break your block, but it does not always happen. Preignition is when it just happens to ignite because it touches a hot piece of metal. Pre Ignition is a form of detonation. And there is no way the air/fuel can ignite other than the compression stroke, because all other times it isnt inside the cylinder. Please do not try to correct me because your ego is bruised, I only do it so people can read things and know what they are talking about. Im not interested in starting any flame wars or "who knows more" contests. I know what I am talking about, And if i dont, I keep my mouth shut. So you should do the same.

How an AFM works
http://www.supracentral.com/content.php?article.88



Detonation and preignition
http://www.misterfixit.com/deton.htm

Closed so I can clean up the garbage that went on in this thread.

Edit - Don't fight, learn to lighten up a bit. I dont want to have to clean anymore threads. supraman121 and kwnate, heres your first warning. dont do it again. and please, a message to the rest of the forum, dont encourage people to fight.

Dont ever buy Venom. Your best bet would be RC Injectors.

had a guy an import tune shop tell me ma70's hit fuel cut at 14.7 psi.

EDIT: of detonation and preignition, here's another good article
http://www.enginehistory.org/wbn/WBN07.pdf

http://zhome.com/ZCMnL/PICS/detonation/detonation.html

there's another article i found in an aicraft magazine a while back that was REALLY good, but i can't find it yet :bah:

i dont think any stock car will make it to 14.7 psi, more like 11-13, 13 if your lucky. Mine fuel cut at 9.5 psi once. And the ct26 can be upgraded to about 400rwhp, but at that point its not going to last very long.

thanx so no venom and on the RC injector which would be the next best upgrade...i heard 550cc buh if i plan on building the internals too would it just b better to upgrade to a 720cc righ away or wait and wha kind of fuel pump would fit best ty