Thread: Question about how much boost I'm running?

Yea my bad... Does that sound about right though? I was hoping for at least 10 that's why I'm asking. I am running 0 KR on this setup. I plan on pulling the motor back apart this winter though going with xp cam, ls7 lifters, 7.00 comp push rods, double roller, 140lb valve springs, with a 3.1 pulley.

So any ideas why my boost is so low? A L36 block and L67 are the same correct? I know my heads are different.

a 1 bar map sensor isn't going to give an accurate enough reading for the pcm to compensate for higher manifold absolute pressure readings. most cars these days will use 2 bar map sensors because 1 bar map's are old technology.

I wouldn't bother changing pushrods unless you need a different length. you aren't going to get more performance out of a different set of pushrods. I would do the 130 lb valve springs instead of the 140's because you want to run the lightest spring to get the job done, and 130 is good for the xp cam. even with that upgraded harmonic balancer you got from zzp, I wouldn't rev that thing higher than 6300 because it isn't going to reduce vibration enough to go much higher. you will get a lot more out of your build if you do a set of ported heads with that xp cam, I recommend the ones that orangeL67 does on here, he doesn't charge near as much as zzp and you get a better product.

as far as boost goes, more is not always better. boost from a supercharger increases the pressure inside the engine, so having low amounts of boost means you have the flow mods set up the way you should. I would do the 2 bar map sensor, and get the tune adjusted, I'm not real sure what would need to be changed, but after that happens if you still have low boost, you might be able to pulley down and then scan for kr

Yes the bbv does move and it whines real loud. Yea I think the higher compression is from the heads so I've heard like a 3.4 pulley on my setup is like a 3.2 or 3.3 on a gtp so it should be higher?

Originally Posted by SgtMarshal

a 1 bar map sensor isn't going to give an accurate enough reading for the pcm to compensate for higher manifold absolute pressure readings. most cars these days will use 2 bar map sensors because 1 bar map's are old technology.

I wouldn't bother changing pushrods unless you need a different length. you aren't going to get more performance out of a different set of pushrods. I would do the 130 lb valve springs instead of the 140's because you want to run the lightest spring to get the job done, and 130 is good for the xp cam. even with that upgraded harmonic balancer you got from zzp, I wouldn't rev that thing higher than 6300 because it isn't going to reduce vibration enough to go much higher. you will get a lot more out of your build if you do a set of ported heads with that xp cam, I recommend the ones that orangeL67 does on here, he doesn't charge near as much as zzp and you get a better product.

as far as boost goes, more is not always better. boost from a supercharger increases the pressure inside the engine, so having low amounts of boost means you have the flow mods set up the way you should. I would do the 2 bar map sensor, and get the tune adjusted, I'm not real sure what would need to be changed, but after that happens if you still have low boost, you might be able to pulley down and then scan for kr

Yea I'm not really worried about the map I have a mechanical boost gauge hooked up. Zzp has it reving to about 6400 right now they said it's benificial to rev higher but not till i put heavier valve springs in. My heads are ported already and they said 7.00 push rods will get me to the happy place with a ls7 lifter stock is 7.05.

Originally Posted by ScottyDoggs

some thing like that. i built boost so fast with the 3.4 on this set up now. i light footed around town for 2 weeks waiting for a puller lol

its got to be the map not reading right, its sounds like your making full boost if you hear the sc screaming. does it feel like its pulling strong and hard? it should if your making full boost.

Yea it pulls strong I just want more hp you can never have to much. How is my map reading wrong when I'm reading it from my mechanical boost gauge I plumed in?

Originally Posted by Tonkin2000GT

Yea I'm not really worried about the map I have a mechanical boost gauge hooked up. Zzp has it reving to about 6400 right now they said it's benificial to rev higher but not till i put heavier valve springs in. My heads are ported already and they said 7.00 push rods will get me to the happy place with a ls7 lifter stock is 7.05.

a mechanical boost gauge and a map sensor are totally different. the pcm is going to use the map sensor to operate the engine. the boost gauge only shows you what is happening inside the engine. you really need to study how an engine works to understand why the different length pushrods are not necessary unless you take measurements and see that you need them. LS7 lifters are about the same length as oem lifters so most people don't change pushrods.

it really seems that you believe everything zzp says without any question. you need to learn more about engines because everything zzp says may be true in some cases, but not entirely.

Originally Posted by ScottyDoggs

some thing like that. i built boost so fast with the 3.4 on this set up now. i light footed around town for 2 weeks waiting for a puller lol

its got to be the map not reading right, its sounds like your making full boost if you hear the sc screaming. does it feel like its pulling strong and hard? it should if your making full boost.

Yea it pulls strong I just want more hp you can never have to much. How is my map reading wrong when I'm reading it from my mechanical boost gauge I plumed in?

Originally Posted by SgtMarshal

a mechanical boost gauge and a map sensor are totally different. the pcm is going to use the map sensor to operate the engine. the boost gauge only shows you what is happening inside the engine. you really need to study how an engine works to understand why the different length pushrods are not necessary unless you take measurements and see that you need them. LS7 lifters are about the same length as oem lifters so most people don't change pushrods.

it really seems that you believe everything zzp says without any question. you need to learn more about engines because everything zzp says may be true in some cases, but not entirely.

Yea I understand how an engine works I built this myself.... I just thought the boost seemed a little low. Ls7 lifters have a tighter range then stock so you need to find the happy medium. Yes I do believe zzp haven't had a problem yet why wouldn't I go with them?????

I was just going to put a L67 map on it but they told me I will need a pcm flash. I wanted a mechanical boost gauge anyways they said it would be easier to just go that route since its my summer daily and id have to wait. I haven't had many issues with zzp and when I did they made it right they do good work i don't know why everyone has to get so hostile and hates zzp I'm just talking? I wanted others opinions that's why I joined the forum everyone on seems to get computer tough guy with me for no reason?