Max 1G hacked MAS flow

[BoostedFWD]

I'm thinking of putting in a big 16G with the stock 450's and want to know at what point the MAS is going to crap out(100% injector pulse) Thanks

[Nick 92 TSi AWD]

You'll need 550s. The mas doesn't affect your injector size, fuel cut has nothing to do with injector size. You'll probably need a 2G mas if you plan on running 17-18psi.
On my friends 90 with a fully hacked mas, ported 14b, 550s, walbro 255, and 17psi he got fuel cut easily. We added a 2G mas and haven't had any problems.

[WGTalon]

I think I have phantom knock for some reason if anyone is familiar with the term. Its a 1g mas....hacked blaha style. I get no knock at 19psi 20g fmic 660's etc through 1-2-3rd gear....soon as it hits 4th bam...the knock comes on strong and timing gets yanked way down to 15-17 vs 21-23 with no knock. I dont see why the car would only knock in 4th unless 4th is where the motor is under more strain and forced to flow more. 2g mas is in the upgrade list or possibly a TRE masc. Just need someway to get around the problem and still retain the 1g mas meter. How the hell does blaha run 130+ on a hacked mas? hahhaha later

[Quadcylla]

I have the same 4th gear knock. I've attributed it to my stock side mount heatsoaking combined with the added strain of 4th gear on the engine.

[BoostedFWD]

I'm running 18psi on my 14B right now with no problem. I want to know if I can do the same on a big 16G.

Nick if you were hitting fuelcut with a 14B and 550's it probably means your MAS wasn't hacked out enough and you were running filthy rich!


P.S. I've heard a hacked 1G MAS can support 25psi on a 14B.(with 450's)

[Edited by BoostedFWD on 07-18-2001 at 02:42 PM]

[Nick 92 TSi AWD]

Actually the entire bottom part of the mas was gone! No flap door though. That's the other thing, o2s were reading .90v and egts were 875c. I think I should stop using Matt's car as an example, it's friggin weird. Same car ran a 13.5@100 with only a 2.5" turbo back, uicp, 190lph walbro, hacked mas, K&N, and 15psi of boost. Pretty damn fast for a measly 15psi.

I should re-phrase my statement, yes it does have something to do with injector size. It's all relative though. With 450s you could run that much boost on racegas very easy. However on pumpgas you will get fuel cut much sooner.

550s and a 2G mas and you're set. mitsu graveyard sells the 2G mas and plug for $100..

[BatmanGSX]

A lot of people are confusing MAF overrun (bucking, hesitating) with fuel cut (engine shuts off briefly). Fuel cut is based on IPW and Injector duty cycle, hacking a MAS and then dumping fuel with an AFC with stock injectors will actually bring you closer to fuel cut.

The only way around fuel cut, really, is to hack the MAS by a certain percentage and run injectors that are close to that same percentage over the stock injectors and FINE tune with an AFC. AFCs were not meant to add +50% across the board to your stock injectors at WOT. If you have a proper setup then AFC settings should be minimal percentage changes for WOT. The big percentage changes were meant for low throttle where you need to lean things out in order not to run rich while cruising or low rpm driving.

Most of us are getting MAF overrun long before we hit fuel cut and we hack the MAS and don't get MAF overrun and think we have "delayed" fuel cut. You never actually hit fuel cut. But the truth is the more you mod your MAS and your car without upgrading the injectors the more likely you are to hit fuel cut.

With a Blaha MAS my friend had completely gotten rid of his 4000rpm/WOT MAF overrun. A little trip to 22psi while messing with the boost and using the AFC with the 450s and we hit fuel cut. It was totally different than MAF overrun and was something neither of us had ever experienced (I thought he holed his pistons but the car was back to normal at lower boost). Later while I was arguing with a smarter man than I, about this very topic (I thought hacking a MAS delayed fuel cut still), he set me straight and I realized what was going on and understood the entire picture.

Hope this info is usefull.

[BoostedFWD]

Well I'm not planning on using an AFC with the Big 16G if I can get away with it, but I see what you're saying. I'd still like to run 18-20psi with just a hacked MAS and 450's. I guess I could always install it and see what happens :)

[BatmanGSX]

I don't think it's a good idea to run a big 16G on stock injectors without an AFC. It's really not a good idea to do all that and then run anything over 15psi. You should revaluate what you want to do with your car. If you don't want an AFC and bigger injectors then I would suggest a small 16G and 15psi as your max turbo size and boost level. Also I would go with a Blaha MAS with flapper in that case.

If you really want the big 16G, or you already have it, and you are set on 18-20psi, get the AFC, some 550s (or better yet 660s and a fuel pressure regulator for maximum fuel cut avoidance), and do some extreme MAS hacking.

[Nick 92 TSi AWD]

Originally posted by BoostedFWD
Well I'm not planning on using an AFC with the Big 16G if I can get away with it, but I see what you're saying. I'd still like to run 18-20psi with just a hacked MAS and 450's. I guess I could always install it and see what happens :)

You will eventually melt every piston. You can't run more than 15psi on a friggin 14b with no fuel control without running lean.

[4G63Rydah]

Originally posted by Nick 92 TSi AWD You can't run more than 15psi on a friggin 14b with no fuel control without running lean.

Says who??...Have you actually tried it? Or done any research about this? Maybe you should do that before you make such a ridiculous post....I know people that have run 20psi on PUMP gas day-in-and-day-out with nothing more than a modded MAS (no fuel control, stock injectors).

[BoostedFWD]

My MAS is hacked Blaha style and I've got a Supra TT pump...

[HighPsi91]

I have run both a 16G and an 18G with 450's.. 21psi on race and 18psi on pump gas... and never owned an afc or the holy datalogger. Went high 12's on pump gas and quicker with race gas. If you hack the mas correct and know what sensor values to fudge... you can make it work real nice and never get fuel cut except on real cold days... and then that just requires more fudging. Al blaha doesnt just use a hacked mas... there are other factors that attribute to fuel cut as well. Mas overrun is a problem that can only be solved by lowering the maximum volume of air going through the metered section of the MAS. Fuel cut is a compilation of things factored together by the ECU.

[BatmanGSX]

Originally posted by HighPsi91
I have run both a 16G and an 18G with 450's.. 21psi on race and 18psi on pump gas... and never owned an afc or the holy datalogger. Went high 12's on pump gas and quicker with race gas.

You are probably more of an exception than a rule. Some DSMs are just freaks. Did you like your 18G? Mine goes on tomorrow...

[Quadcylla]

Last year I was running 20~22 psi at the track with my hacked MAF with flapper door. No S-AFC, stock injectors, stock IC and stock 14b. I did have 110 octane race gas and my datalogger watching the knock. I did not hit fuel cut or MAF overrun. Best time was 13.6 @ 104.

The only reason I could do this safe was cuz I had the datalogger to watch over things for me. I also had a walbro 255 HP to make sure the fuel pump didn't run out. I also monitored the o2 voltage to make sure my 450s were still supplying what they should a the top end. Heck I even did a run at 25 psi. But doing this blindly without a logger isn't too smart. Any one of these things maxing out and you'll have a nice rock you'll have to tow home.

I found the runs at 22 psi were no faster then 18 psi. This is prolly due to the 14b throwing sooooo much heat into the system at that point that it erased any gains from the added boost. On street gas (94) I couldn't run more then 16~17 psi without knocking.

But back to the topic hacking the MAF postpones fuel cut and MAF overrun plain and simple.

Now that I have an AFC and 550s I took the flapper door out but I am still running the hacked MAF (pretty much the whole lower section gone).

[Edited by Quadcylla on 07-20-2001 at 10:57 AM]

[NosLaser]

<<<You will eventually melt every piston. You can't run more than 15psi on a friggin 14b with no fuel control without running lean.>>>

Oh yeah? That's funny, I was runing 20 pounds of boost on a 14B turbo with NITROUS on PUMP GAS on a DAILY BASIS with a 112K mile stock motor. STOCK injectors, stock fuel pressure, no AFC, stock sidemount IC. The only people that tell you not to run more than 14psi on stock fuel control are places like Buschur racing because they want you to buy a VPC, a fuel pump, injectors, and a other miscellaneous go fast parts.

[WGTalon]

Yeah I agree....I ran 12.04@111.93 on big16g Walbro 255hp and a home hacked mas... s-afc and stock smic. So all this junk about 15psi max is a load of crap. Learn from your mitskes trials and tribulations...not speculation. People told me I was crazy for doing it but weekend after weekend i kept doing it. .later

[BatmanGSX]

Originally posted by WGTalon
Yeah I agree....I ran 12.04@111.93 on big16g Walbro 255hp and a home hacked mas... s-afc and stock smic. So all this junk about 15psi max is a load of crap. Learn from your mitskes trials and tribulations...not speculation. People told me I was crazy for doing it but weekend after weekend i kept doing it. .later

Yeah, 15psi is not a "max", more of a safety zone if you don't have an AFC. But my timing gets pulled at around 13psi on my 14B if it's hot out. Go figure... Each car is different.

[Nick 92 TSi AWD]

Um did any of you dip*hits look at my mods before you went along flaming me? No? Didn't think so.

Well on my friend Matt Ahl's 90 awd, at 15psi with a 190lph walbro, hacked mas, and no other fuel system mods he got 875C egts, .89 o2 voltage, and a knock sum of 8 (13.6@100mph at that time). I guess when I hacked the crap out of the mas on my 92, with a stock fuel system, 2.5" catback and boost at 16psi that I didn't get 900c egts, .88 o2 voltage <no logger, no knock data>, that I could have still run 3psi more boost with no problem?
SO YOU ARE ALL TELLING ME THAT CAN NEVER HAPPEN ON ANY 1G HUH? Wow I guess I should come on dsmtalk, the home all these magically tuned, monster hp cars to make sure that my car <and friend's cars> are all really doing what we see them doing huh?
Cool, it's badass that since your cars happen to do something it automatically means that every other dsm in the world will do exactly the same thing.

I guess I'll just shut up now and stay in my corner, since you all know sooooo much more than me, have cars that are oh so incredibly fast.....

f*ck this board. I'm staying on nabr. you idiots aren't even worth my time.

[Nick 92 TSi AWD]

Just to give you a little actual technical info:
maximum hp is given by the formula:

{injector flow rate}x{number of injectors}x{duty cycle}
---------------------------------------------divided--
10.5x Brake Specific Fuel Consumption

Fuel injectors are not designed to operate above 85% duty cycle for even short amounts of time. Their performance becomes very erratic and they normally end up sticking open.

A turbocharged engines BSFC is usually in the .5-.6 range.

So if you assume a .6 BSFC then 450s will be limited to 242.857hp at the FLYWHEEL, or in other words 201.571hp to the drive wheels assuming a 17% drivetrain loss.

With a .5BSFC that would be 291.429hp at the flywheel or 241hp to the drive wheels.

If you are making much more than that then you have taken your injectors out of their duty cycle range. You need better injectors.

Oh and just for sh*ts and giggles at 100% duty cycle and assuming a generous .5 BSFC you could achieve 342.857hp at the flywheel and 284.571hp at the drive wheels.

Go ahead and tell me I'm an idiot. It's all physics.

[BatmanGSX]

Nick has a point, in an angry, deffensive way. I mean have you ever looked at flow data on injectors after they have been sent to RC? It is insane, the variances, even with low miles, between injectors. The ECU doesn't know that one or all of the supposed 450cc injectors is flowing 410cc. Also I've seen cars with the base timing way off stock too, the owners never even touched it. The variances can be so great between two average DSMs that there is no actual rules.

Look at NosLaser, he ran an 80hp dry shot(!)... that is pretty much unheard of in the DSM community. But it worked. Will it work for me? Who knows, I'm not willing to even try. And it goes both ways. Like I stated earlier, some cars are just freaks.

But Nick, you shouldn't get so deffensive. It looked like you had said that no DSM can run 15psi on the 14B without fuel control. I think you meant that in some cases it's possible that you can run lean on the 14B at 15psi without fuel control. Am I correct? In the end I think that you and the others were arguing the same point from opposite ends of the spectrum: there are no rules.

[WGTalon]

Im not flaming on nick at all.....yes I was probably a little on the dangerous side with the 450's and b16g, Ive seen nick's post is several forums and topic areas in here and I cannot argue with his techincal knowledge, so no PUN or flame was intended.

[BatmanGSX]

Yeah, some people I won't argue with. Nick is one of them. I have learned not to argue with NosLaser either. I'm just going to assume that they both will always know more than me.

[IRalliWannaRace]

also psi has nothing to do with actual air flow. For example I think running 18 psi w/ the stock exhaust is actually safer than running 15 psi with a turbo back why because 15 psi, is 15 psi. but it's not 15 psi of boost with the turbo back make lets say 50 more horses than with the stock exhaust so there is actually more air flowing through the engine making the pressure the sam but the air flow higher. also 15 psi from a bigger turbo is more air because A. the exhaust housing creates less back pressure making for more engine air flow. B its more dense because it is cooler and C. Most people on this board don;t know jack about cars and it seems like everyones running 11's when maybe a handful actually are. Everyone on here is like yo, I got a big 16g and I make 450 hp. Yeah BS thats the total extreme limit of that turbo.

[mike5809]

well hes what i run
16g 550inj, bosch feul pump, and removed all honeycombs (cept for one) and took that one screw out in the mas
car runs fine can run 19+psi no fuel cut what so ever....(ran 21 before no fuel cut)
just my input!
oh and idles fine just alittle hard to start up seomtimes

[BoostedFWD]

What are you using to tune with?

[HighPsi91]

Originally posted by BatmanGSX
Originally posted by HighPsi91
I have run both a 16G and an 18G with 450's.. 21psi on race and 18psi on pump gas... and never owned an afc or the holy datalogger. Went high 12's on pump gas and quicker with race gas.

You are probably more of an exception than a rule. Some DSMs are just freaks. Did you like your 18G? Mine goes on tomorrow...



True... some DSM's are more receptive to mods than others. I think alot of it has to do with overall engine condition. I have mixed feelings about the 18G... I have posted in other forums my experiences with it... and just seemed to tick people off. I am sure you will be pleased... unless you are going from a big 16G... then the difference will seem minimal.

[Quadcylla]

"Um did any of you dip*hits look at my mods before you went along flaming me? No? Didn't think so.

Well on my friend Matt Ahl's 90 awd, at 15psi with a 190lph walbro, hacked mas, and no other fuel system mods he got 875C egts, .89 o2 voltage, and a knock sum of 8 (13.6@100mph at that time). I guess when I hacked the crap out of the mas on my 92, with a stock fuel system, 2.5" catback and boost at 16psi that I didn't get 900c egts, .88 o2 voltage <no logger, no knock data>, that I could have still run 3psi more boost with no problem?
SO YOU ARE ALL TELLING ME THAT CAN NEVER HAPPEN ON ANY 1G HUH? Wow I guess I should come on dsmtalk, the home all these magically tuned, monster hp cars to make sure that my car <and friend's cars> are all really doing what we see them doing huh?
Cool, it's badass that since your cars happen to do something it automatically means that every other dsm in the world will do exactly the same thing.

I guess I'll just shut up now and stay in my corner, since you all know sooooo much more than me, have cars that are oh so incredibly fast.....

f*ck this board. I'm staying on nabr. you idiots aren't even worth my time..



What the hell are you talking about??? Who's flaming you??? Who's saying 'that can never happen???

"You'll need 550s. The mas doesn't affect your injector size, fuel cut has nothing to do with injector size. You'll probably need a 2G mas if you plan on running 17-18psi.
On my friends 90 with a fully hacked mas, ported 14b, 550s, walbro 255, and 17psi he got fuel cut easily. We added a 2G mas and haven't had any problems."

Going to the 2G MAF dropped the air-flow (and thus air-mass) value. That's why you avoided fuel cut... since fuel cut is only triggered by air-mass. But since it drops your air-mass value the ECU is gonna give you less fuel... that's why you need the 550s... to compensate.

"Actually the entire bottom part of the mas was gone! No flap door though. That's the other thing, o2s were reading .90v and egts were 875c. I think I should stop using Matt's car as an example, it's friggin weird. Same car ran a 13.5@100 with only a 2.5" turbo back, uicp, 190lph walbro, hacked mas, K&N, and 15psi of boost. Pretty damn fast for a measly 15psi.

I should re-phrase my statement, yes it does have something to do with injector size. It's all relative though. With 450s you could run that much boost on racegas very easy. However on pumpgas you will get fuel cut much sooner.

550s and a 2G mas and you're set. mitsu graveyard sells the 2G mas and plug for $100.."

Running a super hacked MAF on 450s with no fuel computer can be done. You should, however, have some sort of resistance added to the air temp line to richen things back up a bit.

Pleases explain how running pump gas on 450's is going to bring on fuel cut sooner? I'm not flaming you... I'm looking for an explanation because I don't see why. Since fuel cut is based on air-mass I would think that race gas would allow the car to run better (since the knock will be lower) and thus the engine will work harder. This will bring more air into the system thus raising the air-mass value... brining on fuel cut sooner.

Yes 550s and a 2G MAF is a great way to go. The leaness you get from going to the 2G MAF is quite closely matched by the richening of going to 550s. Your air mass values will be lower so fuel cut will be pushed off.

"You will eventually melt every piston. You can't run more than 15psi on a friggin 14b with no fuel control without running lean."

What happens at 15 psi on a 14b that causes you to run too lean? Again I just want an explanation. I have run datalogged runs at 22 psi on my 1G turbo with my 14b and 450s (walbro 255 hp)... it can be done. But it's very dangerous. Without a logger you are really gambling and it's a big risk to run up there since the injectors will max out there somewhere (point is different on car and mods).

The we get to the post you lost it on. You seem to be back to saying you can run more then 15 psi on a 14b. Are you coming or are you going? You've confused at least me here.


Please remember that if you participate in public forums you are gonna get other opinions... what you do with them is your problem. Some will be well educated and some will not. Hopefull ythough proper debate it will be obvious who is in what boat. But to call us all idiots is uncalled for. From the other replies in this thread I don't see all the flames you mentioned and I don't see any ill will towards you. I see debate to points you raised. I don't think your tirade was warranted. Please try to keep things at a 'non-personal' level.

[mike5809]

yo man u need to chill out!
damn u asked us to help and were giving you our honest opinions...some may be right or wrong but there just our opinions that we are intitled to...so just shut up...
not every one is gonna think like u do...so take it easy...

hope u keep running ur car with stock fuel system and ur car takes a shit :)

[Nick 92 TSi AWD]

Did you read my post after the "little tirade" as you would put it?

That was not meant towards you, I'm sorry if you thought it was directed at you. There were two responses that rubbed me the wrong way. I'm not going to get into it.



Your car won't actually be running lean, sorry I should have paid attention when I wrote that. You will be getting your injectors over 85% duty cycle slightly over 15psi on pump gas.
You'll hit fuel cut sooner when you have to richen up the afc on pump gas.....

[WGTalon]

Nick is on the loose again..... Welcome back

[Quadcylla]

Thanks Nick... much better :).

[NINJA7]

Originally posted by WGTalon
Nick is on the loose again..... Welcome back

(*SIGH**) Wow! glad he's back too.

[Zazzster]

My injectors are maxed out with my current mods. I didn't even port my 14b yet. I'm positive that I've hit fuel cut. Since the TMO EPROM install, I haven't felt that jerk since. My MAS is only slight hacked. I do notice that Airflow is maxed out on my Pocket Logger. I just figured I was pulling lots-O-air.

I know that before I buy a bigger turbo, I'm getting an S-AFC and some bigger injectors. Then you can tune what you've got before just plunking in a bigger turbo. It's all fun and games until some one melts a piston.

If you can afford an engine rebuild, you can afford an AFC. Plus they look like a lot of fun. What the hay..... Fuel system, new MAS, FMIC. Go to town...

My two cents....

[BoostedFWD]

Hmmm thanks for the responses. I may just go small 16G since I might be able to get my hands on one for real cheap :)

Zazzster I'm not worried about melting a piston or damaging my engine. I don't see anyway that could happen with my current setup or after the 16G. The MAS is going to crap out long before I ever get 22+ psi on that turbo...

[Quadcylla]

Zazzter... you are gonna hit MAS Overrun with the larger injectors and S-AFC with a lightly modded MAF. Once you have the S-AFC I suggest hacking more from the bottom section.

You can tell you are hitting MAF overrun cuz your air-flow value and inj pulse width will drop off thier peaks and go a bit irratic at the top of a hard run.

[Rdy2race]

MAYBE another time I will go in to a bit more about "why" but here we go

Sup Nick.
To all of you. he is hot headed but he ALSO knows his stuff. Trust me he means well. be happy he is back,

Zazzster
your FAR from out running the 450's The Pocketlogger and all other "loggers" are only reading the ECU OUTPUT not the meter it self. 1600HZ is the max for the output. figureing out Inj Duty cycle is the only way to know. have you done this?? I find it hard to see you maxing out the 450's with out even any porting work on the turbo. Some people have been able to extract 350 HP from the 450's. this is pushing the limit a but but is a 110 trap speed in a full weight DSM AWD. I don't think your doing that with a 14B. you COULD but you do not have the correct set up to make power like that. More thenm likely you just making heat, On the stock I/C I wouldn't push it past 16 PSI as the factor I/C goes to crap after thart amount. With leaded fuel that is a different thing. I am talking street tune.

The TMO ECU puts FC out of range, it DOESN'T GET RID OF THAT. that is IMPOSSABLE as it is in the CODE of the ECU it self. Like Quad said sounds like MAS over run. A AFC should be used with ANY MAS mods. If not that's your own deal but you makeing changes to a calabrated meter and not telling the ECU. This will send you to the school of "hard knock" What kind of knock count are you getting from a DEAD STOP. gun it to WOT around 3500-4500 what is the knock count???


well I wish you the best of luck but don't be foolish many have been where your at now and they are giving advise so you can learn from the goof's that they made and then you don't have to make your own.

good Luck
BM-

[Zazzster]

Thanks for that info. The reason I thought the injectors were maxed is because this is what the TMO EPROM displays. I'm now assuming that this is incorrect. I'd like to put bigger injectors on. But if I can just port my 14b, put on an AFC, and maybe even a TRE high flow MAS, that would suit me fine for now. I do need to do a REAL injector cleaning. My car has about 130k on it. It runs great, and I want to keep it that way.

[Edited by Zazzster on 08-03-2001 at 11:22 AM]

[Nick 92 TSi AWD]

I'm not hot headed Bill ;). I just need to stop smoking so much crack.

[dyezak]

I have run 22psi on a 14b to yield a 13.51@99.99...that equates to roughly 248.2HP, with stock injectors. But the run was with race gas. I'm going to put 550's on my new car with my 19c along with a AFC to be safe though.

[WGTalon]

Ive been following this thread for a while now...and posted on it a couple weeks ago. I recently ran 11.91@115 on my hacked 1g mas with racegas I hacked myself with a dremel too and installed " no resistors" Well I have some bad news to report I went to the track with my new 2g mas with what " I thought" was an awesome tuning setup with timing advance of 23 at 6k with 19-20psi on pump gas. To my disbelief the best the car would go was 12.89@105 on pump gas. All the hc's are still in the mas and the screw hasnt been messed with. I still find it hard to beleive because the 2g mas drop ZERO counts compared to my hacked 1g mas which was dropping counts, hwo do I base this? Look at the HZ screen and graph hz reading on a WOT run and if it looks like a richter scale during an earthquake more than likely its dropping counts, knock is going up and timing is going down. This is what I found......I havent run on racegas yet and 23psi. I dont see 10mph and almost 1 second coming from racegas and tuning. Enlighten me here....have I screwed something up? Later