2g pistons in 1g car... fuel pressure and timing.

[90 GSX]

The only issue with my car is a small boost leak from the throttle body shaft seals. Other than that its in almost excellent shape. All sensors, gaskets, belts, etc. etc. are in perfect working order, all straight from satan... I know the car like the back of my hand. I still get around 7-10 counts of knock with a min of 3-4 and a max of about 13-14. This is at a mere 11 psi. Yes, it is real knock. What I am curious about is whether or not the higher compression of the 2g pistons necessitates more fuel. In otherwords, why do 2g's run more fuel pressure, is it due to the higher compression? Do I need more fuel in this case or an adjustable regulator?

Also, I am assuming that 2g timing maps are different than 1g maps. What do you guys think about putting my base timing down to 3-4 degrees instead of 5* where it is right now.

Thoughts???

By the way, my current mods are in the sig, but for those who are too lazy to look, I have RC550's with a rewired walbro 190 and a dsmchips ecu for the injectors. No AFC, MAFT, or anything or form of tuning.

 

[GVR4592]

1g timing maps are very aggressive, probably too aggresssive for 8.5:1 compression. You can get your chip reburned for 2g timing maps, that should help with the knock. You can try retarding the timing with the CAS, if you don't want to get the chip reburned, but it won't make much difference. Higher compression will usually take a little more fuel because of the increase in torque. A little bump in fuel pressure might help things out a little.

 

[JayRolla]

Yep he is right. Im having the same problem with my 2g pistons. I had 0 counts of knock at 10-11psi and around 30 at 6000rpms running 13psi. Our timing advance is way to aggressive. I turned back the timing to around 2-3 and it helped, I get minimum knock at 13psi now.

 

[BlackWhiteBeast]

I had the same problem but it went away when I rewired my 255lph walbro fuel pump and richened my 5 knob AFC 16% from 4000rpm to redline. I have 550 injectors, 2g mas, 255lph walbro fp, 8:2:1 compression Wiseco pistons, Eagle H-Beam rods, EVO GT exhaust manifold, 2.5 inch turboback, 2600 act clutch and lightened flywheel, Greddy Profec boost controller, Big 16G turbo, and 16 psi with 3-4 counts of knock on the stock sidemount intercooler.

Dont ask why I have a built motor on a 16G turbo or a 255lph walbro without AFPR. I'm upgrading to a Holset HX35 turbo with 650cc injectors and Front Mount intercooler. Also I'll be getting a bolt on AFPR from importevolution.com this week. Well have a nice day and get that knock fixed with more fuel.

 

[andymoraitis]

1g timing maps are very aggressive, probably too aggresssive for 8.5:1 compression. You can get your chip reburned for 2g timing maps, that should help with the knock. You can try retarding the timing with the CAS, if you don't want to get the chip reburned, but it won't make much difference. Higher compression will usually take a little more fuel because of the increase in torque. A little bump in fuel pressure might help things out a little.

Exactly. The 2G ECU peaks at 16 degrees of timing above 2.1 g/rev on the highest airflow table. We can generally run a bit more, but that's a safe spot that will allow for solid boost on pump gas.

 

[andymoraitis]

I'm upgrading to a Holset HX35 turbo with 650cc injectors and Front Mount intercooler

I wouldn't bother with 650's on a Holset since they're way too small. If you plan on running low boost and keeping those injectors, you'd be better off with the 16G. I'd recommend at least 850's if you really want to turn up the boost. 950's would be even better.

 

[90 GSX]

So what do you guys suggest? New chip with 2g maps? Or will putting my base timing down to 2 or 3 degrees btdc work just the same?

As far as the fuel goes... is it worth my money to buy an AFC for fine tuning? The chip is already burned for the 550s... but then again they are RC550s so I don't think they rate their stuff at 38 psi (stock 1g) I think they rate their injectors at 43 psi (stock 2g). Is an AFPR worth my money or would I be okay with an AFC, or do I need both?

 

[nightspeed87]

once my motor 6bolt swap/ rebuid is complete its going to be running 2g pistons also, and i was going to use the n/ts fpr for more fuel pressure but it would be a little drastic i think because the n/t reg bumps fp up to about 47psi which sounds too rich... ( Im also going to have a hacked mass ) Does this sound like im going to be over killing the injectors with fuel pressure or will it be decent since i have 1g timing maps on 2g pistons...

( Only fuel mod I have so far is a walbro highpressure 190lph... Yes i said highpressure, which is already overruning my stock fpr.)

 

[andymoraitis]

The solution to the dealing with an aggressive timing map isn't to drown the motor in more fuel with an FPR that will allow for more overrun. Not only will you run rich, but performance simply won't be there. I'd consider running the Keydiver chip with tweaked maps or something like DSM Link.

Dumping too much fuel at it isn't the solution, but it's better to ask and know in advance than try it and do more harm than good.

 

[nightspeed87]

The solution to the dealing with an aggressive timing map isn't to drown the motor in more fuel with an FPR that will allow for more overrun. Not only will you run rich, but performance simply won't be there. I'd consider running the Keydiver chip with tweaked maps or something like DSM Link.

Dumping too much fuel at it isn't the solution, but it's better to ask and know in advance than try it and do more harm than good.

i see, i remember speaking with your before about the keydriver chips which is definitly a will do but not for another three or four months. I was just considering using the n/t fpr for a temporary solution so i could run about 14 lbs maybe on those 2g pistons with my current set up? I remember mavisky told me back in the day he ran the n/t reg and it allowed him to run more boost ( but he wasnt on 2g pistons and i dont think it will truely compensate for the fact that the 1g timing map is too aggressive for those pistons?? ) seems most 1gers are lucky to get to 13 lbs of boost on 2g pistons huh, so the n/t reg will actually drown performance even if i am able to run say 14lbs on it?

 

[andymoraitis]

It's just not the right solution. You can ward of knocking by adding fuel, but there's no point in doing it to the point at which the A/F ratios become very rich. It's better to run lower boost on a leaner tune than run more boost on an excessively rich tune. This is especially true if we're only taking about 1-2 psi difference.

 

[nightspeed87]

ok i see... thanks

 

[90 GSX]

I had the same problem but it went away when I rewired my 255lph walbro fuel pump and richened my 5 knob AFC 16% from 4000rpm to redline. I have 550 injectors, 2g mas, 255lph walbro fp, 8:2:1 compression Wiseco pistons, Eagle H-Beam rods, EVO GT exhaust manifold, 2.5 inch turboback, 2600 act clutch and lightened flywheel, Greddy Profec boost controller, Big 16G turbo, and 16 psi with 3-4 counts of knock on the stock sidemount intercooler.

Dont ask why I have a built motor on a 16G turbo or a 255lph walbro without AFPR. I'm upgrading to a Holset HX35 turbo with 650cc injectors and Front Mount intercooler. Also I'll be getting a bolt on AFPR from importevolution.com this week. Well have a nice day and get that knock fixed with more fuel.

Is that you blake???? Whatsup brother?

I've been emailing Jeff O from dsmchips.com back and forth for the last few days. I've got everything figured out for the chip but I'm still trying to figure out what to do about the timing... I did little experiment. With my base timing dropped down to 2* i'm getting the same amount of knock at 15psi that I did at 10 psi and 5* base. So I know that the timing maps need work, but is it necessary to drop the timing all the way down to 2g levels? Are they really weak compared to 1g maps, or are they appropriate for a 4g63 with 8.5:1 compression?

 

[Auto RS T]

Is that you blake???? Whatsup brother?

I've been emailing Jeff O from dsmchips.com back and forth for the last few days. I've got everything figured out for the chip but I'm still trying to figure out what to do about the timing... I did little experiment. With my base timing dropped down to 2* i'm getting the same amount of knock at 15psi that I did at 10 psi and 5* base. So I know that the timing maps need work, but is it necessary to drop the timing all the way down to 2g levels? Are they really weak compared to 1g maps, or are they appropriate for a 4g63 with 8.5:1 compression?

When you dropped your timing to 2* you should have left the boost at 10 psi still. By changing the boost, you have added more to the situation, another variable. To do that test it seems you should only have 1 variable, being the base timing. Leave the boost levels alone. Then you will see real results. You can't compare knock changes from changing baseline timing by adding boost when you change the timing also. You only want to test 1 variable at a time.

 

[nightspeed87]

so 2g pistons in a 1g it seems 12 to 13 psi is the basic max amount of boost able to be ran on 1g timing maps correct???

I have a 190 hp walbro and stock injectors, smic, would one think id get to about 12 psi at least with no knock? What if when I get my afpr I increased fp to about 43psi ( the same as the 2gs. ) will this be approriate for the situation.?

 

[slipstream808]

Sure, it'd work if you wanted to run 2g style fuel maps. And then you'd have to tweak them at that.

So pretty much, no. Stick with your base 37psi fuel pressure.

 

[90 GSX]

The point I was trying to make is that 1g timing maps are too aggressive for pump gas and 8.5:1 compression. When I first put my timing down to 2* btdc, essentially all knock was eliminated at 11 psi. The 1g timing maps are not necessarily aggressive, they are pretty accurate for 7.8:1 compression, as are the 2g maps for 8.5:1 compression.

I got a new chip from jeff o. with 2g timing maps extended past 14 psi load to compensate, I will post my results.

The fuel pressure does not make a difference as long as the constant in the program is changed. The only reason 2g's have a higher base pressure is to get a little more out of the stock injectors while keeping the duty cycle down. Correct me if I am wrong, but I believe that as far as target a/f ratios go, 1g and 2g cars are pretty similar.

 

[BlackWhiteBeast]

Hey what's up Omar, I just got my Aeromotive AFPR kit from importevolution today and I'm getting ready to install it right now. Hopefully I can run a little more boost with lower IDC's by raising my base fuel pressure to 43psi. I know my Walbro 255lph fp was overrunning my stock fpr so hopefully things will work out a little better for me.

I have my afc +14% rich across the board from 3200rpm to redline to combat the knock that I get at 16psi; this is due to my 2gen mas and 550cc injectors. Hopefully I'll be able to lean it out a little for more timing by turning up my base fuel pressure. I'll be getting a fmic, AEM UEGO wideband, and DSMLINK next week so my tuning will be pretty much set after that.


P.S how'd the new 2g timing maps work out for you?

 

[90 GSX]

I'm putting the new chip in this weekend. I got my afpr yesterday too... I built the kit myself for about 300 bucks (about 100 more than the IE kit). Aeromotive afpr, -6 an fuel rail feed and return fitting, fittings to eliminate banjo bolt on top of fuel filter with -6 an fitting, -6 an steel braided lines from filter to rail, rail to afpr, and afpr to fuel return on firewall, plus a gauge on the afpr. It's going to be sick. I also have a dejon intake and 2g mas I'm putting in at the same time... should be quite a nice modding round, but the chip is the key. Anybody with 2g pistons can't run 1g timing. I think at WOT 1g cars run about 4-5 degrees more timing than 2g cars, enough to cause endless knock problems.

 

[nightspeed87]

I'm putting the new chip in this weekend. I got my afpr yesterday too... I built the kit myself for about 300 bucks (about 100 more than the IE kit). Aeromotive afpr, -6 an fuel rail feed and return fitting, fittings to eliminate banjo bolt on top of fuel filter with -6 an fitting, -6 an steel braided lines from filter to rail, rail to afpr, and afpr to fuel return on firewall, plus a gauge on the afpr. It's going to be sick. I also have a dejon intake and 2g mas I'm putting in at the same time... should be quite a nice modding round, but the chip is the key. Anybody with 2g pistons can't run 1g timing. I think at WOT 1g cars run about 4-5 degrees more timing than 2g cars, enough to cause endless knock problems.

This being said even on 10-12 lbs of boost???


I plan on getting my eprom chipped in the future to a more suitable timing map
for the 2g pistons but for now should I still be ok at 12lbs is what im asking?

 

[slipstream808]

Do you have any way to monitor knock? Now that's the question.

Because if you can run a 1g timing map at that boost without a problem than go for it. But if you can't monitor knock, I personally wouldn't try it. At least WOT. You could drive it around day to day with no problems most likely.

 

[90 GSX]

This being said even on 10-12 lbs of boost???


I plan on getting my eprom chipped in the future to a more suitable timing map
for the 2g pistons but for now should I still be ok at 12lbs is what im asking?

Even at 12 psi you probably have some knock. Get an ebay logger and check your knock counts and timing, that's the only way to tell. Talk to Jeff at dsmchips, he made me custom hybrid 1g/2g timing tables. I'm sure he'd be happy to give them to you when your order an eprom. There are certain regions that have more timing relative to the 1g's and vice versa, he took that into account. I'll let you know how it goes.

 

[nightspeed87]

ok thanks, I will have to do that... What about on stock boost with 2g pistons in 1g will I still get knock even then? I just dont want it to be dangerous to the engine till I get it going right and its on an engine Im about to be breaking in soon.... Dont want to break it in with knock you know..

 

[TKI]

I just installed 2g pistons in my 1g. Looks like I need to get a logger ASAP. I have my boost set at 16 psi, so I think that Im gonna be turning it down to 12 psi or so.

What is the weblink for the Keydriver chips? What do I need to tell them as far as the settings? Im still not real clear on it.

 

[nightspeed87]

[email protected] is an email address I was referred too that I just emailed myself today... The guys name is jeff I believe...
Try these sites , this is where I was looking http://www.dsmchips.com/~keydiver/
www.dsmchips.com

Seems to be interesting info on here...
And yea 16lbs sounds dangerous on 2g pistons with stock 1g maps, turn that down to 11 lbs even you dont want to destroy your engine over something like this.....