• The site migration is complete! Hopefully everything transferred properly from the multiple decades old software we were using before. If you notice any issues please let me know, thanks! Also, I'm still working on things like chatbox, etc so hopefully those will be working in the next week or two.

Advice Needed on Stock Supercharger

9

98gtpne

New member
Hi ,

I am new to this so please forgive me if I am posting this in the wrong spot, but I am looking to get a bit more horse power out of my GTP, and hoping some master minds on here can provide some advice. The car is currently stock with the exception of a new intake. In the next month I will be getting a 34 pulley, and cat delete done.

I have a friend who has a 2003 cobra and he has his stock supercharger ported and gained quite a bit of hp. I was wondering if u can do the same with the stick GTP supercharger amd if so what kind of power performance will i get from that. Also if you have an idea of how much something like that would run, that would great as well.
 


blower porting doesnt really get you much until youre out of the efficiency range of the blower, which is in sub 3.0 pullies. to run those youll need a lot of mods.

and dont delete the cat...just dont...
 
why do you say dont remove the cat? I have a friend with a 02gtp and she had the cat and u-bend removed and dynode a bit higher. i pretty much wana do a 3.4 pulley the exhaust work and better tires and further down the road do a 3.0pulley and meth injection..
 
who cares about a 2 hp gain from making your exhaust sound like crap? leave the cat. the stock catback isnt a restriction up until like 350 whp.
 


Did you read the modding your 3800 thread that was posted above earlier? If not, read it and if you still have questions and then ask. You are asking things that have already been posted in that thread. take fifteen minutes and read it.........now, before asking anymore questions. Questions always get asked like this and for the most part are already answered in that thread.............we will be more than happy to answer any more questions that you may have after reading it. Thank You.........
 
^yes...and no. I for one believe that the stock cat is a restrictive SOB, and that the exhaust tone doesn't suffer much from removing it - as compared to the resonator. As for actual # gains...not so much, but if you're going to start dropping pulley sizes - you need to FIRST invest some money into the exhaust - ie; u-bend removal, and larger downpipe...if you're going to do that...get rid of the cat or go with a hi-flow cat at the same time...it just makes sense.
HP gains from porting the inlet/outlet of the blower (virtually none, BTW) will always be argued, but there is no disputing the fact that it makes the blower more efficient and that is a good thing. Lowering the outlet temp is very useful for future pulley drops and tuning.

My standard reply to fairly cheap and easy instant HP gains:

NOTE: You can find all of this used - check the For Sale section for demods, etc.

1) Delete the U bend, upgrade to a downpipe and remove the cat entirely or get a DP with a hi-flow cat. Avg. cost - $125 - $200
2) Get a set of 1.9 roller rockers and 105 lb springs. Avg. cost - $225 - $300
3) Drop spark plugs to one step colder, ie; Autolite 104's. Avg. cost - $20
4) Drop pulley size to 3.5", not 3.4. This might be harder to come by - it isn't a popular size and is usually a press-on style, where modular would be ideal. Avg. cost - $25
5) Tune, tune, tune. Nothing you bolt on, press on or remove will matter at all, if you don't tune the car afterwards. Avg. cost - Free/12 pack, etc...if you can find someone to help you out that has a tuner.
6) BONUS - if you can afford it - get with Trannyman95 and get 3.29's, a hardened 4th gear(not for performance, but longevity), and a shift kit installed. IMO - the BEST bang for the buck mod for these cars. You have to drive one with these to understand. Trust me.

Nick's (bluegtp91) post has just about everything you need in it. But the real simple rule of these cars is - they need to breathe, and they need to be tuned.

-Swash
 
U-bend delete with the downpipe should be one of the first, if not the first and most necessary mod......along with a CAI or FWI.........in short you must first be able to get the air into and out of the motor more freely than it is stock to start modding the vehicle to have it work properly......(read pulley drop)
 
Swash said:
^yes...and no. I for one believe that the stock cat is a restrictive SOB, and that the exhaust tone doesn't suffer much from removing it - as compared to the resonator. As for actual # gains...not so much, but if you're going to start dropping pulley sizes - you need to FIRST invest some money into the exhaust - ie; u-bend removal, and larger downpipe...if you're going to do that...get rid of the cat or go with a hi-flow cat at the same time...it just makes sense.
HP gains from porting the inlet/outlet of the blower (virtually none, BTW) will always be argued, but there is no disputing the fact that it makes the blower more efficient and that is a good thing. Lowering the outlet temp is very useful for future pulley drops and tuning.

My standard reply to fairly cheap and easy instant HP gains:

NOTE: You can find all of this used - check the For Sale section for demods, etc.

1) Delete the U bend, upgrade to a downpipe and remove the cat entirely or get a DP with a hi-flow cat. Avg. cost - $125 - $200
2) Get a set of 1.9 roller rockers and 105 lb springs. Avg. cost - $225 - $300
3) Drop spark plugs to one step colder, ie; Autolite 104's. Avg. cost - $20
4) Drop pulley size to 3.5", not 3.4. This might be harder to come by - it isn't a popular size and is usually a press-on style, where modular would be ideal. Avg. cost - $25
5) Tune, tune, tune. Nothing you bolt on, press on or remove will matter at all, if you don't tune the car afterwards. Avg. cost - Free/12 pack, etc...if you can find someone to help you out that has a tuner.
6) BONUS - if you can afford it - get with Trannyman95 and get 3.29's, a hardened 4th gear(not for performance, but longevity), and a shift kit installed. IMO - the BEST bang for the buck mod for these cars. You have to drive one with these to understand. Trust me.

Nick's (bluegtp91) post has just about everything you need in it. But the real simple rule of these cars is - they need to breathe, and they need to be tuned.

-Swash
Click to expand...
why do you say go with the 3.5 vs. the 3.4? How much HP are you really losing out on with .1 inches here?(assuming it is tuned)
 


Liquifire said:
why do you say go with the 3.5 vs. the 3.4? How much HP are you really losing out on with .1 inches here?(assuming it is tuned)
Click to expand...

It isn't about the HP you're "losing" - it's about the KR that you're not gaining. A 3.5 can actually give a higher gain in HP because of the lack of KR that comes with it. Case in point - if you currently run a 3.4 with 0-2* of KR at WOT - and say you run 13.9-ish. If you take that same car and put a 3.3 or 3.25 on it - you will likely run slower - because the increase in KR that is going to rob HP. In my '02 GP I had 1.9 RR's, 105# springs, 3" DP, PEM's, FWI, NGK plugs, ported SC and ported TB, 3.29's and shift kit - all on a fresh rebuild that ran a 14.0X on a 3.4 pulley on a 90* and humid day - it would have run 13.8X easily, but I forgot to turn on performance shift in the PCM :(. It had a DHP v1.0 tune with only trans tweaks to accomodate the 3.29's. I had only blips of KR at WOT, so I decided to drop to my 3.25 and run. I ran almost .2 slower - and had 4*-6* of KR at WOT. With the 3.4 - had I had perf shift enabled - I would have seen 13.8X at 100+ without anything more than a canned tune. With further tweaking, I would have been able to drop to a 3.3 or 3.25 and gotten to maybe 13.6X.

The point I'm trying to make is - there are a lot of cars out there that pop soon after a 3.4 pulley is installed. It's the most popular "instant gratification" mod out there and damage occurs mostly due to ignorance as to the potential consequences. A 3.5 will still provide a noticeable gain - without the huge jump in KR that typically comes with a 3.4.

Getting off my soapbox now...

-Swash
 
thanks for the replies. I have already orderd the 3.4 pully and new belt and the new plugs and wires so i guess i will get the dp next and then take it in and get tuned.. im really just looking for 25hp more then stock for little more power since this is the daily driver. maybe someday i will get crazy and put alot ot time in money in it but for now i just need it quicker cause it was really slow all stock..
 
Swash said:
It isn't about the HP you're "losing" - it's about the KR that you're not gaining. A 3.5 can actually give a higher gain in HP because of the lack of KR that comes with it. Case in point - if you currently run a 3.4 with 0-2* of KR at WOT - and say you run 13.9-ish. If you take that same car and put a 3.3 or 3.25 on it - you will likely run slower - because the increase in KR that is going to rob HP. In my '02 GP I had 1.9 RR's, 105# springs, 3" DP, PEM's, FWI, NGK plugs, ported SC and ported TB, 3.29's and shift kit - all on a fresh rebuild that ran a 14.0X on a 3.4 pulley on a 90* and humid day - it would have run 13.8X easily, but I forgot to turn on performance shift in the PCM :(. It had a DHP v1.0 tune with only trans tweaks to accomodate the 3.29's. I had only blips of KR at WOT, so I decided to drop to my 3.25 and run. I ran almost .2 slower - and had 4*-6* of KR at WOT. With the 3.4 - had I had perf shift enabled - I would have seen 13.8X at 100+ without anything more than a canned tune. With further tweaking, I would have been able to drop to a 3.3 or 3.25 and gotten to maybe 13.6X.

The point I'm trying to make is - there are a lot of cars out there that pop soon after a 3.4 pulley is installed. It's the most popular "instant gratification" mod out there and damage occurs mostly due to ignorance as to the potential consequences. A 3.5 will still provide a noticeable gain - without the huge jump in KR that typically comes with a 3.4.

Getting off my soapbox now...

-Swash
Click to expand...
what exhaust mods did you have with your 3.4 setup? Just curious because I was going either PLOG or headers with DP and never plan on going beyond the 3.4 setup. Assuming you have no knock it would be safe on a 3.4 in your opinion? So basically just using a 3.5 to play it safe. I am completely stock on the pulley and never have any knock yet......always O.O........good for now.

Saw you had PEM's and DP........missed that the first time around....Do you think you would have any KR if you had either headers or PLOG?
 
Last edited:
98gtpne said:
thanks for the replies. I have already orderd the 3.4 pully and new belt and the new plugs and wires so i guess i will get the dp next and then take it in and get tuned.. im really just looking for 25hp more then stock for little more power since this is the daily driver. maybe someday i will get crazy and put alot ot time in money in it but for now i just need it quicker cause it was really slow all stock..
Click to expand...
It has to breathe first.........you will NEED a downpipe and PLOG or headers first(before the pulley) otherwise you will just have crazy KR and pulled timing up the A$$....Also have the PCM installed at the same time or you will not be realizing any power potential that you will have...........fwiw.
 
Swash said:
It isn't about the HP you're "losing" - it's about the KR that you're not gaining. A 3.5 can actually give a higher gain in HP because of the lack of KR that comes with it. Case in point - if you currently run a 3.4 with 0-2* of KR at WOT - and say you run 13.9-ish. If you take that same car and put a 3.3 or 3.25 on it - you will likely run slower - because the increase in KR that is going to rob HP. In my '02 GP I had 1.9 RR's, 105# springs, 3" DP, PEM's, FWI, NGK plugs, ported SC and ported TB, 3.29's and shift kit - all on a fresh rebuild that ran a 14.0X on a 3.4 pulley on a 90* and humid day - it would have run 13.8X easily, but I forgot to turn on performance shift in the PCM :(. It had a DHP v1.0 tune with only trans tweaks to accomodate the 3.29's. I had only blips of KR at WOT, so I decided to drop to my 3.25 and run. I ran almost .2 slower - and had 4*-6* of KR at WOT. With the 3.4 - had I had perf shift enabled - I would have seen 13.8X at 100+ without anything more than a canned tune. With further tweaking, I would have been able to drop to a 3.3 or 3.25 and gotten to maybe 13.6X.

The point I'm trying to make is - there are a lot of cars out there that pop soon after a 3.4 pulley is installed. It's the most popular "instant gratification" mod out there and damage occurs mostly due to ignorance as to the potential consequences. A 3.5 will still provide a noticeable gain - without the huge jump in KR that typically comes with a 3.4.

Getting off my soapbox now...

-Swash
Click to expand...


not gona lie sounds like way to much work for a high 13
 


but i guess i just got the car not to long ago and havnt had much time to read up into the gtp's.. I really only hear of 13sec gtp's i read about a couple 12sec ones is it just hard to build or coast alot.. well i guess i cant say much about money my other car has a **** ton in it but i look my car up on any forum and running a 11 isnt anything to talk about idk just struck as odd since i thought alot of people build gtp's but most are into 13's maybe 12's
 
Well then all I can tell you is sit down and read then. IF you put that pulley on before doing anything more than a u-bend delete a stock GTP would eat you for lunch. And for the record...you dont NEED all of those mods to run those times...a tuning guru on here...I think his name is Mike...tuned a BONE STOCK GTP and went 14.4 @ 98...stock pulley, everything. Just goes to show you. Get the PLOG, get the 3" catted or catless downpipe and get rid of the u-bend...get a lower temp t-stat, colder plugs (autolite 104's), new wires if necessary...make a intake, get a tuned PCM (DHP, Intense, or Overkill)...THEN put your pulley on...and find a way to scan for KR.
 
98gtpne said:
not gona lie sounds like way to much work for a high 13
Click to expand...

??? The only internal change was rockers and stiffer springs...about a 1 1/2 hour job. The other stuff...that's just how it should have been - GT's have 3.29's - the GTP's should have, too, but they didn't because of MPG impacts (that and they knew the trans was a turd), porting that was done wasn't so much for HP gains - but for ease of tuning and effeciency. The FWI and exhaust changes were something that I would have done to increase MPG as well as support any performance mods. So - really - not much "work" at all for a +1 second 1/4 mile improvement.

-Swash
 
bluegtp91 said:
Well then all I can tell you is sit down and read then. IF you put that pulley on before doing anything more than a u-bend delete a stock GTP would eat you for lunch. And for the record...you dont NEED all of those mods to run those times...a tuning guru on here...I think his name is Mike...tuned a BONE STOCK GTP and went 14.4 @ 98...stock pulley, everything. Just goes to show you. Get the PLOG, get the 3" catted or catless downpipe and get rid of the u-bend...get a lower temp t-stat, colder plugs (autolite 104's), new wires if necessary...make a intake, get a tuned PCM (DHP, Intense, or Overkill)...THEN put your pulley on...and find a way to scan for KR.
Click to expand...

all orderd and car goes in on sat for cat and u-bend delete..
 
You must log in or register to reply here.
Back
Top