2g pistons and spool time

[want_a_gsx]

those of you out there that have 2g pistons in a 1g motor, how much of a difference did you notice in your spool? how much were you boostin? what rpm did it hit full spool w/ what turbo?

 

[want_a_gsx]

anyone?

 

[GVR4592]

Higher compression won't noticeably affect spool times.

 

[95blackGsTurbo]

I put 2g pistons in my 92 I rebuilt and spoolup was 200rpm better but that is probably because of a rebuilt motor with new compression numbers. Just depends on how bad your motor is right now.

 

[nightspeed87]

i dont think you gain spool time, it will feel more torque mainly in off boost, thats all. Your 1g timing maps are too aggressive to run any appreciable amount of boost on 2g pistons without link, or a chip. Maybe not worth the trouble ( I have 2g pistons but im chipped also.)

 

[95blackGsTurbo]

I ran 23 psi on a EVO III 16G with just an SAFC I and EVO injectors and showed no knock on 92 pump.

 

[nightspeed87]

I ran 23 psi on a EVO III 16G with just an SAFC I and EVO injectors and showed no knock on 92 pump.

but my point is that you have 2g timing maps. 1g timing maps are far more aggressive and rise faster , and according to another dsmer ive spoken with who was running that set up ( without the chip ) on his 16g he couldnt run anything over 13lbs without knock on stock 1g timing. Of course theres the possibilty his car had other problems but I dont think so; 1g had 7:8 comp ratio in mind and 8:5 is considered a big difference when the stock timing maps go into the 20s. Correct me if im wrong but I dont think 2gs even go over 16 deg timing adv stock.

Fortunantly for the thread poster , shows he has a 91 gsx. Good chance he has an Eprom then, and I would just suggest he'd do like I did and go to www.dsmchips.com and talk to Jeff about a custom hybrid 1g/2g timing map set up for those pistons if he did go that route, and get a lot of other chip features while he's at it.

 

[want_a_gsx]

i dont think you gain spool time, it will feel more torque mainly in off boost, thats all. Your 1g timing maps are too aggressive to run any appreciable amount of boost on 2g pistons without link, or a chip. Maybe not worth the trouble ( I have 2g pistons but im chipped also.)

no eprom here but i am planning on getting an eprom (when i complete the rebuild) with keydiver chip----"custom" 2g timing and all the great features like injector compensation, etc.

I put 2g pistons in my 92 I rebuilt and spoolup was 200rpm better but that is probably because of a rebuilt motor with new compression numbers. Just depends on how bad your motor is right now.

120, 90, 15, 75 compression right now...so full boost @ 5k

well getting the motor rebuilt will DEFINITELY decrease spool but i just wanted to know if 2g pistons in 1g would decrease the rpm at which the 14B reached full boost.

i mean, to me it makes sense that it would because of the higher compression but i could be wrong...

 

[bluegs-t]

Higher compression won't noticeably affect spool times.

i know someone that thinks otherwise; however, he can't prove that it does.

 

[AuntiesTSI]

i know someone that thinks otherwise; however, he can't prove that it does.

Relax Shawn

 

[bluegs-t]

Relax Shawn

haha!! it's funny because i don't get anywhere with him.

 

[JayRolla]

Im running a rebuild motor with 2g pistons in my 1g. My timing never even drops under 18* at onset of boost and goes up to about 26* by redline. It causes all kinds of knock past 12psi without fuel control.

On the question realistically, you dont notice any difference between compression change. When you get to adding boost and tuning thats where you get your power.

 

[want_a_gsx]

Im running a rebuild motor with 2g pistons in my 1g. My timing never even drops under 18* at onset of boost and goes up to about 26* by redline. It causes all kinds of knock past 12psi without fuel control.

On the question realistically, you dont notice any difference between compression change. When you get to adding boost and tuning thats where you get your power.

were you able to offset the effects of knock caused by the higher compression on a given amount of boost using SAFC/DSMLINK, or did you go nightspeed87's route and get a custom chip?

 

[GVR4592]

i know someone that thinks otherwise; however, he can't prove that it does.

I know a guy that thinks he can fly given the right conditions....

 

[want_a_gsx]

explain???

 

[blackGSX2g]

explain???

Lots of LSD and a 5th of vodka

 

[JayRolla]

were you able to offset the effects of knock caused by the higher compression on a given amount of boost using SAFC/DSMLINK, or did you go nightspeed87's route and get a custom chip?

Not yet since I dont have timing control. If you get a SAFC then you wont beable to fix the timing. You need dsmlink or a burned chip.

I would just need the Acid and ill be flying.

 

[andymoraitis]

i dont think you gain spool time, it will feel more torque mainly in off boost, thats all. Your 1g timing maps are too aggressive to run any appreciable amount of boost on 2g pistons without link, or a chip. Maybe not worth the trouble ( I have 2g pistons but im chipped also.)

Good job RJ. That's absolutely correct. I saw no difference in spool going from 8.5:1 to 8.8:1 but the sensation of torque was different. The biggest effect on spool is achieved with increased displacement. With respect to the timing maps, swapping to 2G pistons almost always necessitates a change to a 2G map which peaks at 16 degrees max above 2.1 g/rev unless you want to run high octane fuel all the time or install methanol injection to squelch the knock.

 

[JayRolla]

Yep since im not going to have timing control untill I get an eprom, im going with meth injection and hope I can still get some good power on pump even with my 24* advanced timing. I hate it so bad.

 

[andymoraitis]

You'll be fine like that Jason since you'll have the best of both worlds. High timing combined with higher compression and more boost will feel fantastic. I'm not sure where the 1G map peaks above 2.1 g/rev but your timing may be so high because you're on a very low airflow map and nowhere near peak airflow to kick the ECU onto that high load map.

Maybe someone with intimate 1G ECU knowledge can chime in and offer some information.

 

[want_a_gsx]

You'll be fine like that Jason since you'll have the best of both worlds. High timing combined with higher compression and more boost will feel fantastic. I'm not sure where the 1G map peaks above 2.1 g/rev but your timing may be so high because you're on a very low airflow map and nowhere near peak airflow to kick the ECU onto that high load map.

Maybe someone with intimate 1G ECU knowledge can chime in and offer some information.

so are you are you also saying that a eprom and chip are required or are you saying he should stick with the 1g timing?

 

[JayRolla]

Good point Andy. I wonder if up here in this thin air if that has an effect also. I never thought of that.

Want_G_GSX if you want full capability of your set up than yes dsmlink or something to control the timing is needed. Since im going with just a safc, im going to get meth to compensate for the 1g timing advance. Hopefully it works great.

 

[want_a_gsx]

Good point Andy. I wonder if up here in this thin air if that has an effect also. I never thought of that.

Want_G_GSX if you want full capability of your set up than yes dsmlink or something to control the timing is needed. Since im going with just a safc, im going to get meth to compensate for the 1g timing advance. Hopefully it works great.

yeah just gonna get eprom and keydiver. should do the trick...

what are the downsides of having 2g timing maps instead of the stock 1g timing?

 

[andymoraitis]

Omar,

If you run the stock 1G maps with higher compression pistons, you'll have a tendency to knock on pump gas since higher compression raises cylinder temperatures. Pump gas isn't very knock resistant so you wouldn't be able to run much boost without knocking and pulling timing.

Let me know if that helps,

Andy

 

[want_a_gsx]

Omar,

If you run the stock 1G maps with higher compression pistons, you'll have a tendency to knock on pump gas since higher compression raises cylinder temperatures. Pump gas isn't very knock resistant so you wouldn't be able to run much boost without knocking and pulling timing.

Let me know if that helps,

Andy

yup, very clear. thanx