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Discussion Starter · #1 ·
One of my best friends does port and polish work for mustangs (he did my PI heads and they flowed just about as well as some big name company stage II heads), anyway I finally drove by to show him my new, and very different, Cobalt. He said he wouldn't mind doing some port work on the Eaton, TB, and even the head. My question is, what are the effects/gains/losses of port work on a 4 cylinder? Any positive or adverse effects to look for as opposed to doing it on a bigger displacement v8?
 

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cant tell you exactly however i talked to a guy that does a lot of tuner work and has an eclipse thats got just over 440 to the wheels, iv seen the dyno sheet. anways he recomended that i do that. he said that the gains are amazing even on a 4 banger
 

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on the m90 s/c, when they get p/p, you usually drop 2 lbs of boost which is around 2 pulley sizes smaller. i was really surpised how well my p/p blower helped me car.
 

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zeez gtp said:
on the m90 s/c, when they get p/p, you usually drop 2 lbs of boost which is around 2 pulley sizes smaller. i was really surpised how well my p/p blower helped me car.

so if you get it done, you will need to put on smaller pullies to get the same boost?
 

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Discussion Starter · #7 ·
selfinfliction said:
so if you get it done, you will need to put on smaller pullies to get the same boost?

Yeah, well I'm not sure if it is the same idea on a smaller displacement motor...but I know on the 4.6l v8 port and polish work has a huge impact on boost with roots style blowers. My friend had a saleen series II (M90) on his mustang and he was running 12 psi on a stock motor. With a smaller pulley and forged internals he upped it to around 18psi. Soon after, he had bought some VT PnP stage II heads and cams, and also had the M90 ported by magnesun (sp). After doing this, with the same same pulley that was pushing 18psi, it now produced 13psi at full boost. It made more power from all the work on the motor, but it was still a catch 22. I *think* it has to do with the big increase in airflow through-out the motor, and the decrease of pressure build-up (please do correct me if I am mistaken).
 

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i don't know much about blower porting....


but if we are running 14,000 rpm with our blowers now to get about 12.5 psi, and we port it we have to run smaller pulleys, to make it run the same amount of boost(after PnP), and our blowers are not recommended for over 14,000 rpmr... it doesn't make sense to me. now i know the m90's run @ 12000rpm, so maybe them jumping up in speed is no problem, but not so sure about ours

if anyone actually knows about this stuff... please post it cause i'm really curious now
 

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it's like, you lose boost, but it's good because you are running the same power with less boost. I would rather run less boost at the same power and not have the car work as hard. It helps create less boost stacking and cools the inlet/outlet air which will prevent knock.
 

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zeez gtp said:
it's like, you lose boost, but it's good because you are running the same power with less boost. I would rather run less boost at the same power and not have the car work as hard. It helps create less boost stacking and cools the inlet/outlet air which will prevent knock.

oh so you don't necessarily lose power, it's just much more effecient at the boost it does make... i get it now
 

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Technically speaking from seeing the cnc head for the 1000hp+ eco tech at the autorama. The ports aren't where the power is, it's the valve area that needs the attention. The upper bowl area, around the valve stem, to the port is where the power is made. I have done complete port & polish and mil to a head on my first gen neon. I can tell you it will help the car, it makes the car feel more lively & peppy. I don't think it's worth it for the cash vs hp made. Mine blew the head gasket, so the party was on cams, titanium retainers, springs, and P&P. :D 7800rpms :D With the SS I would just turn up the boost, Trust me when I say that the best power adder for the car is more psi, up until its at about 90-95% efficency of the blower. If I had a SS mods would be pulley, intake, exhaust, done safely. If you want more than that, well son, be the front runner, for all of us to follow. :rolleyes:
 

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i plan on definitely getting my head PnP work done, just not until i can get me a beater car to drive. as for the blower... i'm just not sure on yet
 

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you lose boost due to the enlarged ports in the motor, which takes away boost pressure, but you get more volume, which is better. 13psi on an m90 will create just as much power as 18psi on an m62, because it the 90 produces more volume.
 
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