Higher comp pistons. Nedd a tune?

[DJYoshaBYD]

ok.. Im building a stock 6bolt with wiesco 9.0:1 comp pistons in my 1g TSi AWD... I chose them higher than stock so I could get better spool time, especially when I swap in the 16g... Im going to be running the car at stock boost until the motor is all broke in...

My question is, is the stock ECU going to run the car right or do I need an SAFC to tune a little bit? What should I watch out for, besides a super fast spool time with my 14b... haha

 

[DJYoshaBYD]

ok, so nobody knows?

 

[Low Impedance]

so you went from a 7.8 to a 9.0 compression? if i understand you correctly.

 

[JayRolla]

Get a logger, im pretty sure you will be fine. You wont beable to boost more than 9-11psi most likely.

 

[Raph]

Well after you get a wideband and a tuning device..turn up the boost..

i boost 14-15 psi on 9.7 compression(4g63 na-t).. and that since 2 years ..nothing went boom yet.

and the off boost response is excellent.

Yes im a High Compression fan

edit: the evo 3 has 9.0 or 9.1 ..so..

 

[fourreGsixty3]

Yes he went from a 7.8:1 to a 9.0:1 CR. Just to let you know the compression will not spool the turbo faster, it will help with off boost tq. though, and that will make it "feel" like its spooling the turbo faster, but that would be minimal. As long as you have fuel upgraded, and are decent at tuning you wil be able to run decent boost, but that level of boost will be lower then the same set-up with a 7.8:1 CR due to the fact that the higher the CR, the risk of knock is increased due yto more heat being made from the same amount of gases being compressed that much more. Definately a logger, tuning, and fuel. Also since you are upgrading your turbo, Im guessing you have other mod's, and to get the most potential out of those mod's you should get some sort of tuning device, I would go with Link, or a custom chip (what Im getting in a couple months).

 

[DJYoshaBYD]

ok.... but isnt 9.0 still fairly low? I see people swapping 2g pistons on their motors all the time to bump up compression.... thats exactly what I did, but with after market pistons.... so now I cant run even stock boost without doing some fuel mods? Is that what Im hearing?

 

[DJYoshaBYD]

Im going to get an safc, if that will help....

 

[DJYoshaBYD]

oh.. and I got a metal head gasket... that should lower my compression a bit...

I just read that evos run an 8.8:1 ratio.. with the thicker head gasket, I should be right there...

Does anyone know where I can get a good, cheap, used SAFC? Im just going to need it if I want to pass the sniffer...

Im in stockton, ca. if anybody has one

 

[JayRolla]

oh.. and I got a metal head gasket... that should lower my compression a bit...

I just read that evos run an 8.8:1 ratio.. with the thicker head gasket, I should be right there...

Does anyone know where I can get a good, cheap, used SAFC? Im just going to need it if I want to pass the sniffer...

Im in stockton, ca. if anybody has one

Actually your compression is pretty high. 2g pistons are 8.5:1. Its all in the tuning and race gas works great with high compression.

For you safc go on ebay, but you shouldnt need one to pass the sniffer if you run your stock fuel.

 

[DJYoshaBYD]

can i run stock boost?? 11 psi?

 

[nightspeed87]

can i run stock boost?? 11 psi?

High compression is good if you have the means to tune everything and are trying to squeeze every bit of
power you can. For a person that doesnt have fully ability to tune but still wants to run some moderate amounts of boost
and timing then id say leave compression alone which I learned the hard way. Besides you make more power by raising boost and timing than by adding compression. And in by adding compresion you cant raise boost or timing to the same extent most of the time unless you have a means to fully tune ( like i was saying. )
At 11psi you may get some knock. Id get a logger immediately if I were you.
Its not your fuel system that will cause the knock, its the fact that your 1g timing maps will be too aggressive for that kind of compression. You need to have a way to change/ tune your timing maps. Even 2g pistons ( 8:5.1 comp ) ratio
is known to cause knock on the stock 1g timing maps at anything over 13psi. When i ran 2g pistons i had to get chipped to put 2g timing maps ( which are less aggressive/ less timing adv as 1gs.) , I just had them 30 % expanded.
I mean theres a lot of factors, but Id connect the j pipe nipple directly to the wastegate actuator to leave the boost down as far as possible ( unless you have a mbc. ) Id only run like 9psi till you get a logger and a tuning device that can lower timing and im not talking about safc because with larger injectors that will only raise timing. Let me know if your lost?

 

[DJYoshaBYD]

im not going with bigger injectors yet... and Im only running stock PSi... so what? I need a DSM link? what can I use to control timing if I cannot use a SAFC to control it?

I can make a MBC in my sleep... I am already planning on making one for this car.... Im not turning up the boost AT ALL until I get an SAFC and the motor broke in...

As for the high compression, I fuc*ed up.... I got 9:1 pistons just to bump up the CR a bit so I could be harder no in boost.... but I guess I got the ratio too high... at stock boost I should be fine.. after that im going to need to tune the hell out of the car... which is fine with me... I can do it and I have MMCD and the datalogger cable for the laptop to run the datalogging software... all i need is an SAFC...

If any of this sounds wierd, just let me know... Im pretty sure I got this on lock...

My MAIN GOAL is to have this motor last a while, still be fast, and pass smog right after the break in... as long as I can smog this at stock specs, then I will do whatever I have to do to make it go fast (tuning, fuel, boost, etc..)...

does this make sense

 

[nightspeed87]

im not going with bigger injectors yet... and Im only running stock PSi... so what? I need a DSM link? what can I use to control timing if I cannot use a SAFC to control it?

I can make a MBC in my sleep... I am already planning on making one for this car.... Im not turning up the boost AT ALL until I get an SAFC and the motor broke in...

As for the high compression, I fuc*ed up.... I got 9:1 pistons just to bump up the CR a bit so I could be harder no in boost.... but I guess I got the ratio too high... at stock boost I should be fine.. after that im going to need to tune the hell out of the car... which is fine with me... I can do it and I have MMCD and the datalogger cable for the laptop to run the datalogging software... all i need is an SAFC...

If any of this sounds wierd, just let me know... Im pretty sure I got this on lock...

My MAIN GOAL is to have this motor last a while, still be fast, and pass smog right after the break in... as long as I can smog this at stock specs, then I will do whatever I have to do to make it go fast (tuning, fuel, boost, etc..)...

does this make sense

I noticed you have a 91, therefore check to see if you have an eprom ecu and if you do just send it to jeff at dsmschips.com and tell him your goals and what compression your running and he'll make you custom timing maps to fit your compression and then youd be able to run all the boost your fuel would permit. What I was saying with the safc is i know that when you install bigger injectors to compensate for the larger injs and what not it also raises timing in the event of tricking the ecu of its actual air flow value. Doing this will further raise timing and increase knock for your high compression situation. Since your in cali and have piss fuel 91 octane that makes it even worse in your scenario. Good thing you do have a logger to tell your knock value. You could manually pull timing back at the cas if your knocking too much but it wont help too much as its the ignition advance in the timing maps that'll be the main culprit. A eprom ecu, a dsm chip, or link will solve your problems and make tuning so much easier.

 

[DJYoshaBYD]

jesus H!!! I got 3 infractions in 20 minutes....

is the DSMlink easy to tune? I had an AEM EMS for my honda and that thing was complicated... but at the same time, it was a stand-alone ecu...
Im going to take my ECU out today and see if its an EPROM.. if it is, its still going to be a while before I can send it in, because I have to work and I cant be without my car for too long...

you think that if I used octane booster in the car and left it at 11 psi until I get new timing maps it would be fine?

 

[nightspeed87]

octane booster wont help much , and i would just stay with 9 or 10 psi for the time being

 

[DJYoshaBYD]

ok... probably 9.... I hope im still sitting at 195hp.... I mean, I shouldnt loose to a stock gsx when I am done because I am making up the boost with a higher compression.... o well... we will see... there's this cocky SRT4 that needs to be taught a thing or 2 about speed.... but thats after my break in....

 

[nightspeed87]

ok... probably 9.... I hope im still sitting at 195hp.... I mean, I shouldnt loose to a stock gsx when I am done because I am making up the boost with a higher compression.... o well... we will see... there's this cocky SRT4 that needs to be taught a thing or 2 about speed.... but thats after my break in....

two things, you probably wont beat a str4 at your current power,
and also compression wont make up for less boost, it is the least power adder.
Timing and boost is where it counts. Also 9- 10psi should be fine, look into that
chip stuff I was telling you about because you couldnt go wrong that way and would
thank me later. And on top of that, there are other things you can do in the meantime to
go faster such as weigh reduction. Depends on how far you want to go with that car.

 

[DJYoshaBYD]

I just got out of a fully gutted honda, so its keeping interior.... I didnt mean get the srt4 now... when I finish the break in and turn up the boost and fix the timing....

I just finished the engine yesterday.... all I have to do is bolt on the turbo, fuel rail, xfer case, and axel... the start it...

Im going to get ecu chipped as soon as I can... hopefully I can find some one in NorCal who can do it... I cannot be without my car for that long....

While I am waiting for the break in period to end, Im going to drop it about an inch all around and make a 3 inch cat back for it....

 

[nightspeed87]

sounds good and anyone with ecu knowledge and chip downloading experience can chip it. Question is would you trust it? I went to dsmchips, and got it done by jeff because hes good and reputable. Either way youd be ok i guess, just take it easy till you get it chipped to fix those timing maps.

 

[DJYoshaBYD]

yeah.... im still going to run at 9 psi for a while too.... would an MSD box help? I can get them dirt cheap from my business... I just dont want to have my car out of commission and I dont have the cash to buy another ecu.... they are, like, 200 bucks, right?

 

[nightspeed87]

for one theres weight reduction that can be done without it looking gutted.
and for two msd isnt really going to help your situation because they arent
commonly used by the average dsmers because supposebaly our ignition is already strong enough, and if we do upgrade ign ppl normally opt for coil on plug set ups.your whole issue is too much heat from high compression and too much advance in your stock timing maps. Ignition has nothing to do with it. just make sure you use the best octane you can get , keep the boost low as possible and set out to order your chip asap.....