dkorinko Posted March 24, 2006 Report Share Posted March 24, 2006 I was just curious if anyone knows what the "stock" boost level should be on a 1997 GTP, my only mods as of right now are a cold air intake, NGK plugs, and a full 3" exhaust, u bend deleted, 3" to 3" maganflow cat and then when it gets back to the tips it goes down to 2.5". No mufflers. The reason why i am asking is because I hooked up an autometer book gauge and I am seeing boost readings as high as 11 psi. It typically stays around 7-9 psi but then once the rpm's get up there it jumps to around 11psi. I was just wondering if this was normal and if anyone else has had a similar experience??? Quote Link to comment Share on other sites More sharing options...
dbtk2 Posted March 24, 2006 Report Share Posted March 24, 2006 With no u-bend I would expect your boost to be a little lower, but that is about right. A stock GTP should see around 7psi at most rpms but above 5k the boost will start climbing to around 11psi at the shifts like you say. That is normal. This is why you can't go with a significantly smaller pulley because you can only run around 11-12psi safely on an L67 with an M90 and no intercooler, and since at high rpms it already reaches that with a 3.8 pulley it doesn't take much of a drop in pulley size to get into some serious trouble. Getting 14+psi before the shifts is not that hard to do and that can become a big problem. Also, you can't be sure your boost gauge is 100% correct either. Shawn Quote Link to comment Share on other sites More sharing options...
99RegalGS Posted March 24, 2006 Report Share Posted March 24, 2006 Factory specs for boost is 7-9 lbs. Quote Link to comment Share on other sites More sharing options...
john99gtp Posted March 24, 2006 Report Share Posted March 24, 2006 yea that sounds about right, since you have a somewhat free flowing exhaust going. i remember for a couple weeks, before i did my headers, i was pushing 12, and 15 on shifts, needless to say, i only did that once. now with an IC, i wonder what i could push, but i bet i cant drop pulley sizes to much, since im still getting KR on shifts and takeoffs (happens about 1 out of every 5) im actually scared to goto a 3.2 Quote Link to comment Share on other sites More sharing options...
dkorinko Posted March 24, 2006 Author Report Share Posted March 24, 2006 Well its good to hear that what i am experiencing is pretty normal, on my way home i am going to pick up some 100 octane and see how the car likes or dislikes it. I am curious to see how these cars respond to high octane fuel. I am counting down the days till march 31st, thats next pay day and i will be able to order my new pcm Quote Link to comment Share on other sites More sharing options...
john99gtp Posted March 24, 2006 Report Share Posted March 24, 2006 octane may or may not help you it all depends on what kind of timing / knock retard you got going on now. dont be disappointed if it does nothing, that just means your car is in good running order, unlike mine, where its like a whole new animal if i use 100octane (or used to be, since i had a lot of knock retard, which higher octane helps fight) what pcm you shooting for? Quote Link to comment Share on other sites More sharing options...
dkorinko Posted March 25, 2006 Author Report Share Posted March 25, 2006 The one on http://www.pfyc.com seems to give some pretty impressive gains, I believe they show about a 14 wheel hp gain with it. Is there anything else you guys would suggest??? Quote Link to comment Share on other sites More sharing options...
digitaloutsider Posted March 25, 2006 Report Share Posted March 25, 2006 DHP or bust. If you're showing any boost readings over 8 psi or so on a stock pulley, you're boost stacking. Quote Link to comment Share on other sites More sharing options...
dkorinko Posted March 25, 2006 Author Report Share Posted March 25, 2006 Well I dont have a stock pulley anymore lol so i guess that doesnt matter anymore. What online places sell the DHP PCM?? Quote Link to comment Share on other sites More sharing options...
slowmontecarlo Posted March 25, 2006 Report Share Posted March 25, 2006 Click here to see Video That was with a stock pulley. Only real mods were DHP, 9" K&N and flowmaster 40s. Defiently stacking up a bit but KR was pretty minimal and I ran a handfull of 14.1xx@98 like that. Quote Link to comment Share on other sites More sharing options...
dkorinko Posted March 26, 2006 Author Report Share Posted March 26, 2006 Sweet Video, so i would assume that the DHP PCM helps out a handful??? Quote Link to comment Share on other sites More sharing options...
dbtk2 Posted March 27, 2006 Report Share Posted March 27, 2006 Sweet Video, so i would assume that the DHP PCM helps out a handful??? As far as power, not really. You'll gain a little power due to reduced torque management and fuel and timing tables, however the biggest gain is the different shift points, rev limiter, and speed limiter. You can't go wrong with a DHP, especially for $100. I don't think I would've put a pulley on an L67 car that already had 11psi. I sure hope you went with a 3.4 or 3.5". Shawn Quote Link to comment Share on other sites More sharing options...
digitaloutsider Posted March 27, 2006 Report Share Posted March 27, 2006 So.. were you seeing 11 psi with the stock pulley or the 3.25"..? Quote Link to comment Share on other sites More sharing options...
dkorinko Posted March 27, 2006 Author Report Share Posted March 27, 2006 It was spiking to 11psi with the stock pulley. Now with the 3.25" I get between 9-14PSI. Obviously with this much more boost I am very careful with the throttle. Which I will continue to be until I get my PCM and intercooler. Quote Link to comment Share on other sites More sharing options...
dbtk2 Posted March 27, 2006 Report Share Posted March 27, 2006 What do you have for exhaust and intake mods? Even with a PCM and SS intercooler, if you keep your stock intake and keep your ubend and whatnot you will still probably get some KR. If I were you I would do a 3" downpipe w/u-bend delete and some sort of intake and a PCM before doing an intercooler. Then with an SS intercooler you MIGHT kill most of your KR. You'll probably need some colder plugs and a colder tstat though. (autolite 103 or 104 plugs and a 180 tstat) Higher ratio rocker arms would be good too. You're defiantely modding a little out of order so it will probably take you a while to be happy with what your car does. I'd be willing to bet that our '04 Monte with ~$600 in mods would walk all over your GTP after you put on your intercooler even though the Monte has a bigger pulley (3.4") and no intercooler, this would be wth the same amount of $ invested. I'm not quite sure why you were so dead set on the 3.25" pulley. If you mod the right way, your car will keep getting faster as you mod and you don't have to worry about blowing stuff up, and in the end you'll be just as fast as the next guy who thought if he modded all halfassed and backwards he could make his car fast cheap when in reality he really didn't. And you wouldn't have to drop $500 at a time. You can spend $100-$150 at a time and make a good difference. Then after you do all that stuff, you can put an intercooler on it and actually get a pretty big gain because you have supporting mods. 14psi non-intercooled on an M90 is REALLY pushing it. My dad runs 14psi with a full intercooler and a cam and still gets kr from time to time. The most I would push it non-intercooled is ~11psi. But as long as you keep your foot out of it ALL THE TIME you should be okay. Shawn Quote Link to comment Share on other sites More sharing options...
dkorinko Posted March 28, 2006 Author Report Share Posted March 28, 2006 Current mods are: Full 3" Exhaust, u-bend delete, magnaflow cat and no mufflers. 3" Intake. NGK TR6 Plugs. 160 Degree Thermostat 3.25" Pulley. And I will be ordering the PCM within the next week. Quote Link to comment Share on other sites More sharing options...
dbtk2 Posted March 28, 2006 Report Share Posted March 28, 2006 What kind of intake. Fenderwell or CAI? If its just an open filter it is actually worse than the stock intake. You still really need some sort of valvetrain mod, whether it be rockers or a cam. Does that 3" exhaust include the downpipe? Also, if you have stock manifolds it might not be a bad idea to get some ported ones, or headers. Pushing air through a restrictive engine is going to do nothing but cause a lot of heat. I'd do some 1.9 rockers or a cam, and then after that go with an intercooler and you will be happier with your setup. Without letting the engine flow more air you won't see a lot of gains. Realistically with the setup you have now, plus the PCM you are talking about, 1.9 rockers, and an SS intercooler, and your car should be running pretty well with that size pulley and you should probably not have any KR, as long as you have some way to tune the fuel (powertuner, mini-afc, etc..). Then with some ported manifolds or headers you would be doing pretty well. Before doing too much I'd find someone with a scan tool so you can scan for KR and adjust your 02's or invest in one yourself. Shawn Quote Link to comment Share on other sites More sharing options...
99RegalGS Posted March 28, 2006 Report Share Posted March 28, 2006 Honestly I don't see why you guys are having a big fit about his pulley choice still. He has it, it's done. My friend did a similar thing as him. He bought a 3.25" pulley after only doing 3" exhaust from the cat back (including a ubend) and a Gutted airbox. He had a spike of 6* of kr. Not good, but I've seen much much worse on other cars. after he got a 3" DP it dropped to IIRC 4* KR. Has hasn't scanned it since he added a DHP and since he made a new intake. Is he still getting KR? I'm sure he is. Is it much? No. He's still deciding what he's going to do but he' probably going to do PEM's and 1.8 rockers very soon. That'll kill any KR that he has left. Quote Link to comment Share on other sites More sharing options...
dkorinko Posted March 28, 2006 Author Report Share Posted March 28, 2006 I am about 2 clicks away from ordering the DHP PCM, is there anything else for the same amount of cash I should be considering before i order this thing? From what I hear this will be about the best 100 bucks spent but I just thought I would double check, thanks! Quote Link to comment Share on other sites More sharing options...
digitaloutsider Posted March 28, 2006 Report Share Posted March 28, 2006 Order it. Quote Link to comment Share on other sites More sharing options...
dkorinko Posted March 31, 2006 Author Report Share Posted March 31, 2006 DHP PCM has been ordered!!! Local exhaust shop said they would not charge more then 20 bucks to install the 3" downpipe so that looks like it will be the next step, anything else i should be doing before i throw the new downpipe on there?[br]Posted on: March 30, 2006, 04:25:41 PM_________________________________________________No suggestions??? Quote Link to comment Share on other sites More sharing options...
sl3196 Posted March 31, 2006 Report Share Posted March 31, 2006 Make sure to replace donut gaskets on both ends. Can order them from GM. Quote Link to comment Share on other sites More sharing options...
john99gtp Posted March 31, 2006 Report Share Posted March 31, 2006 yea, or youll get an uber cool exhaust leak sound like i got my car sounds like ass when its cold Quote Link to comment Share on other sites More sharing options...
dkorinko Posted April 1, 2006 Author Report Share Posted April 1, 2006 Make sure to replace donut gaskets on both ends. Can order them from GM. Exhaust shops would not have these handy??? Quote Link to comment Share on other sites More sharing options...
cutlassdude96 Posted April 1, 2006 Report Share Posted April 1, 2006 they may have to order them Quote Link to comment Share on other sites More sharing options...
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