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What is the safest boost spike a stock fuel system can handle with a T25?

Cause I had my boost controller set at 15psi and we had a cold front come through and I spiked to 17psi and it only fell to 14psi till redline. I tried to do it again, but I guess the ic, etc... were heat soaked so boost never passed 15psi and fell to 13psi. (But it was not boost spike, just the crappy T25)

Just curious....

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'99 GST
http://www.geocities.com/mospeed9844
Akimoto Air Fitler
GReddy BOV
GReddy Intercooler Piping
GReddy Cat-Back
GReddy Profec B
GReddy Boost and EGT Gauge
Autometer Air/Fuel Meter
Front and Rear Strut Bars


[This message has been edited by mospeed (edited October 09, 2000).]
 

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when i first got my 2g, all i had for mods was a k & n filter, and a 3" turbo-back and both side honeycombs out of the mas. well i ran 25psi several times and used to scoot around town at 22psi and it ran fine. at 25psi i was running .89 o2 voltage. these things run so rich from the factory that i don't think you can run it lean with a t25, even at 25psi(i have seen stock 2g cars datalogged at .96 o2 voltages). i listen to all these guys saying they are running 15psi max and if it goes to 18psi "oh my god shez gonna blow" and i just laugh. MAN TURN THAT SH IT UP !!! these engines can handle 400hp bone stock and you guys are scared to go past 18psi. even with the little t25 these cars have nothing going on untill 20psi. granted the t25 won't last very long at 25psi but that will give you an excuse to get a bigger turbo when it dies. i remember back when i had the mods listed above and nothing more...i would run it at 15psi then crank it to 22psi and damn, probably around a 75hp jump. it's not easy to blow up a 4g63, they are real strong engine's and can substain lots of detonation, unlike my civic where if it detonates once..."whoa that was close", detonates twice and "bang" the funs all over.
for the guys that are running 15psi and have never seen 20psi, you'll probably sh it your self when you feel the differance from 15-->20psi...on a t25, letalone a 20g or bigger.

also just to get some smiles....i had my stock 2g bov(you know the plastic one everybody throws away)holding 25psi all day long, overboosted(tony) can vouch for me on this subject....hehe man i was broke back then :D :D :D

bill

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95 tsi-awd
91 tsi-fwd
95 civic turbo
82 gti
 

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I thought the main reason why people don't go higher than 20psi with their T25 is because by then, it's just running hot air. The stock IC can't cool that much, and so you aren't gaining much (if anything) by turning it up. I've always heard it's probably faster to go ~18 than 20+. But that's just from my experiences, your mileage may vary.

Jack
 

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I agree with higher boost, a week after I bought mine I set my my boost up to 19lbs. spiking almost 22lbs. as far as just pumping hot air , as long as you keep over 40 mph the intercooler stays reasonably cool, only hard light to light draging will you suffer the warm intercooler. My t25 has no play yet after two years, mind you that , afer 300 miles I performed my first full sythetic oil change, and still do to this day.

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Randy on the spot
99 GS-T
 

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okay, i have a 97 GSX and have only had it for a couple of months. as of now i'm mostly stock unfortunatly, but that slowyl but surely will change. anyway, right now i have a Boost, EGT, and A/F gauge; an aircharger; and a test pipe in place of the cat. a 1G bov and an MBC are ordered as well.

once i get these installed, will i be able to run 18-19 psi at the track? will this be okay on stock fuel system and ic? the spike after this pressure is my real concern.

this topic already touches on most of this stuff, but (as far as i know) safe boost levels vary so much with different mod levels i just wanna make sure i'll be okay. thanks,
PAUL
 

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paul;
19psi should be ok, but your gonna have to experiment with taking your honey combs out. start with the bottom and if that's ok then put that back in and take out the sides. if not you might get fuel cut at 19psi, but every car is different, i didn't get fuel cut till after 20psi.
just be carful and add the boost slowly, you'll like the outcome :D

bill

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95 tsi-awd
91 tsi-fwd
95 civic turbo
82 gti
 

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<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by sublime:
I thought the main reason why people don't go higher than 20psi with their T25 is because by then, it's just running hot air. The stock IC can't cool that much, and so you aren't gaining much (if anything) by turning it up. I've always heard it's probably faster to go ~18 than 20+. But that's just from my experiences, your mileage may vary.

Jack
<HR></BLOCKQUOTE>

yes this is true, you don't want to get out on the open road and run your t25 and your stock i/c wide open at 22psi for miles and miles, the stock i/c will heat soak fast. usually when i would go out to race around on the weekends i would only be at full boost(22-25psi) for no more then 10 seconds then i'd be putting around cooling the i/c awaiting an unsuspecting mustang or f-body.
anytime you can up the boost on a turbo you are gonna get more flow, the turbo might not be very efficient at higher boost but you'll get more flow. there is a point where the turbo just can't make anymore boost...on a t25 that's about 27psi.

bill




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95 tsi-awd
91 tsi-fwd
95 civic turbo
82 gti
 

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Paul 97 GSX,
Don't forget about the fuel system. Its all stock and won't be able to handle the higher boost pressures. Keep and eye on the A/F and EGT, you'll know when you go lean (+1650F). If that happens replace your pump with a higher flowing one like a walbro or denso for those higher pressures. You'll probably be able to get away with your stock injectors, for now ;)

Zach
'92 Laser RS Turbo AWD
"RSX"
 

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Chemist, why is it that I can overboost my dsm with my A/F gauge still showing rich? Here's another maybe stupid question, can the master brake cylinder make clicking "like" sound under heavy boost? Since it needs vacuum to operate? It really does sound like it on my car :confused:

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Small 16G
2G Ported o2, 2.5 Greddy DP, 2.5 Test / High Flow, 2.5 Greddy Catback
Spearco FMIC (not installed yet)
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Greddy ProffecA, Greddy Timer, Custom A/F Gauge,
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Thanx Chemist! I guess it's time to get an EGT gauge :) My engine has about 20K after I've rebuild it, including all four new pistons, I'm thinking of redoing it again, this time with different pistons (JE) and new oil pump since I can't get rid of the valve noise, I might also install a balance shaft removal kit, But that's a big project and it may have to wait until next summer :)

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Mike,
HKS Mega Flow
2G Ported ExhaustManifold
Small 16G
2G Ported o2, 2.5 Greddy DP, 2.5 Test / High Flow, 2.5 Greddy Catback
Spearco FMIC (not installed yet)
2.5 CMV UIP
Greddy ProffecA, Greddy Timer, Custom A/F Gauge,
VDO's

 

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TurboMitsu,
I'm not sure on the master cylinder question, sorry.

With respect to the A/F readings. As I'm sure you're aware you can't compare O2 voltages between cars. Everyone's car is different. I personally know of one person who can't run any leaner than a 0.90v or its bad news. Others can run it down to 0.85v without melting anything. So when you get a A/F gauge and see that it stays rich at overboost the gauge is telling you what it sees , the voltage. But, that voltage means different things with repect to your cars condition. A rich reading on the gauge might be at 0.91v, but like my friend that's his border line. Understand? (is it clear enough?) To properly tell what the A/F voltages are doing on your car you need to also look at you EGT's. The combination of the 2 tell you exactly what you can run. Used together they provide the information necessary for fine tuning your vehicle. If a A/F gauge is on your christmas list, I would recommend getting a digital read out like a jumtronix. Even a Digital Multi-Meter would work (ugly though). The autometer A/F gauge is a nice looker, but really when you smash the gas do you know exactly which colored bar to look for? If you don't have an EGT but really want to start tuning (like me), take baby steps, and don't let the O2 go below 0.90v to be safe. If you let it drop much farther without the EGT , you could start melting things. Then you will get a letter to join the DOTC (Driving Over The Crank) Club.

This is just my $0.02, Your Milage May Vary.

Zach
'92 Laser RS Turbo AWD
"RSX"
 

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20K and another rebuild? How come other than JE pistons, (think crower rods :)), balance shaft removal, (ported head :))? You know you could sell your 20K rebuild and buy a fully done Buschur with all the bells and whistles.

Just a thought,
Zach,
'92 Laser RS Turbo AWD
"RSX"
 

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When I got my 2g I had a fuel pump 3in and FMIC..BOV..I pulled off the wastegate line and drove around pushing all the boost I could. Never ran lean..Turbo died in two weeks though :) Didn't care had a new on at home. Just wanted to see how fast I could go at the track 13.4 at 101mph car was fast but had no topend.
Ryan
 
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