Boost v.s. Timing

[Andy0x1]

Has anyone had an experience playing with less boost / more timing v.s. more boost / less timing?

I run an L67 with Gen3 M90.

Ported heads / notched block / ported M90 / 9:5:1 Pistons / Air/water Intercooler, Ported Stock MAF with bulky sensor removed, and an LS6 MAF mounted further upstream.

I run a 2.8" pulley.

Car just barely pulls on an 08 C6 with an LS3. Practically even. Beats it by about 3 car lengths by 120mph.

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Should I be running faster with those mods?

(This is on 91 octane pump gas and big heavy 20" wheels / tires)

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I own a Jeep Limited (5.7) as well, and my buddy has the SRT-8 Ver. That thing surprised me, it's about the same as the C6, but faster out of the hole.

[Eddie-98GTP]

All things being equal, boost beat timing but not by a whole lot. At the track about 2 years ago, I did this experiement. Running a 3.2 pulley (with current mods minus ported heads) and 19* timing, I was running in the 13.3 range consistaintly. Dropping to a 3.0 pulley and lowering timing to about 16 degrees got me in the 13.2 range. Then, adding 105 octane fuel, I was able to raise my timing to about 19* running the 3.0 pulley - this netted me my PB of 13.025, but I was VERY consistaintly running 13.0xx. All of this was done at the same track on the same day with pretty much the same temps.

I am currently running a 3.4" pulley, 93 octane fuel, and commanding 17* at WOT with AFRs in the 12.0-11.8 range. I know I could add a little fuel and raise timing a little, but it runs just fine as it is. I don't see the need to push anything for daily driving. I killed a 2006 Mercedes Benz SLK55 last week, so I'm happy as it sits now

Hope this helps

[danthurs]

It will depend on how much timing you are loosing. If your running a 3.0" with 15* of timing your better off going to a 3.1" and pushing 17* or 18* I just tuned a GTX and he has 22* with a 3.0" and we dropped to a 2.8" and dropped him to 18* Still good timing with such a small pulley.

[ssms5411]

I don't think you can compare a SRT8 to a 08' C6 LS3 435HP. The SRT8 weighs about 4200-4300 LBS while the vette is 3200 LBS. Thats around a 1000LB difference = to about 100HP. Esp. off the line the SRT8 would be a dog compared to the Vette. How much HP are you running if your keeping up with a 08' C6 vette? Also whats your weight of the car?

[chrisb]

[QUOTE=Andy0x1;170861]Has anyone had an experience playing with less boost / more timing v.s. more boost / less timing?QUOTE]

Dont for get that it all depends how the efficently the boost is made. So its going to be different for a car with a turbo compared to one with a m90.

[Perforator]

I think the Vette was playing with you.

[murphinator]

I think the Vette was playing with you.

his mods should put him solidly in the 12's and you never know who can and cannot drive their car. I beat an 08 zo6 at the track with my 13 sec buick guy was a customer of mine that didnt know how to run it .After hooking him up with a regular there with a zo6 for some instruction he got down to 12.5's.

the vette the poster is talking about is an ls3 not an ls7 add a possible lack of driving skill and it sounds about right

[02GTP]

Car just barely pulls on an 08 C6 with an LS3

your smoking something good for that one. an LS3 vette would flat out murder you. i just got rid of a GTP that ran a 12.6@112 on street tires. xp cam, ported Gen3 M90, ported heads, zzp stage 3 i/c, built 3.29 trans, full 3" exhaust. i couldnt touch an LS3. i got pulled by a LS2 GTO with 370whp and he got his ass kicked by a stock C5z which would also loose to an LS3 vette.

but in regards to your question, yes the car will make more power with more timing/less boost. especially considering how inefficient the M90 is and how much heat it makes. after 9lbs or so, each pound of boost is less than 10whp, more like 5 (according to zoomer who owns zzp). whereas timing will get you more power and the iat will be lower due to lower boost, making even more power.

[Andy0x1]

I don't think you can compare a SRT8 to a 08' C6 LS3 435HP. The SRT8 weighs about 4200-4300 LBS while the vette is 3200 LBS. Thats around a 1000LB difference = to about 100HP. Esp. off the line the SRT8 would be a dog compared to the Vette. How much HP are you running if your keeping up with a 08' C6 vette? Also whats your weight of the car?

I'm not 100% sure if the (Jeep) SRT8 was stock or not, but yeah, it was MUCH faster then I was expecting, like you, I didn't belive it when people were talkign about it. But after racing it.. yeah, it was quick... Esp for a SUV. Unreal.

My car is stock weight, unless you consider the heavier wheels, dynamat, and Intercooler. The only weight reduction that comes to mind are the baer breaks with alluminum hats, but the fact that they are 12" instead of 10.9 likely negates even that.

[Andy0x1]

your smoking something good for that one. an LS3 vette would flat out murder you. i just got rid of a GTP that ran a 12.6@112 on street tires. xp cam, ported Gen3 M90, ported heads, zzp stage 3 i/c, built 3.29 trans, full 3" exhaust. i couldnt touch an LS3. i got pulled by a LS2 GTO with 370whp and he got his ass kicked by a stock C5z which would also loose to an LS3 vette.

but in regards to your question, yes the car will make more power with more timing/less boost. especially considering how inefficient the M90 is and how much heat it makes. after 9lbs or so, each pound of boost is less than 10whp, more like 5 (according to zoomer who owns zzp). whereas timing will get you more power and the iat will be lower due to lower boost, making even more power.

Well there's your problem putting ZZP parts in the car. I've had nothing but problems with ZZP... Their 3.69 gear kit had un-nessesary screws installed to secure the reluctor wheel to the input gear (that backed out and destroyed my transmission.) - (got caught in the chain and snapped it in two)

I had a DUB (Dial Ur Boost?) hub that wouldn't fit their own pulleys as the tollerances were off.

Their underdrive alluminum water pump pulley goes out of round as its too soft.

I can only imagine the mess they made of the heads in the porting process?

....

In any case, I find it interesting that I'm getting the opposite reaction than I was expecting. I was thinking my car was running slower then it should in the fact that it barely pulled the LS3 Vette...

[Andy0x1]

Come to think of it, I've had many more problems then that with ZZP, but that was a long time ago, and it's all water under the bridge.

[02GTP]

i dont mind zzp, 99% of their parts worked awesome. i had some problems and zoomer worked with me to get them resolved. zzp>intense in my opinion. Intense Gen 1 LSD FTMFL. anyways, if u had slicks u might be a ET race for a stock LS3 but an LS3 is the faster car. any sort of roll race or race that goes over 80mph is bad news for you. do u even know what an LS3 vette traps?

[Andy0x1]

We went from a roll, I moved over to the outside lane going ~30 and waited as he was comming up from behind, then got on it just as he was about to pass; as soon as he heard my tires light up, he got on it too. He had momentem on me, and got about 2 car lengths up and kind of hung out there for a couple seconds before I started to creep back slowly, he shifted clean but I obviously have no way of telling how many R's he was giving it. by about 100 I was level with him, and by 120 I was a car length ahead. He honked and gave me the thumbs up...

[02GTP]

sorry, dont believe it, especially from a roll and ESPECIALLY, how u came back from 2 lengths and put a length back on him, NO WAY. i wouldnt even believe that against an LS2.

about the same as the C6

that doesnt make sense on so many levels. an SRT8 Jeep is not on the same planet as an LS3 vette for acceleration. or anything else for that matter except for cargo room.

[Andy0x1]

For what it's worth:

Just some random quote off the web:

"A soccer mom can launch an SRT8 Cherokee and I watched one (not a soccer mom) run three 12.6's in a row last month at the track. Only mod was a cold air intake."

Racing it from a stop is stupid on cold street tires.