How to Begin Mods to Your 3800 powered car

Questions to ask are

  • Can you do complex installs yourself?
  • How much do you want to spend?
  • Will you continue to upgrade your car in the future?
  • Do you have a factory warranty?

For every person with a Series II 3800 the SC pulley swap should be the first thing considered. It offers the largest HP/dollar value of any mod. You will need a special tool to do the install which can be bought or rented. Install time is about 1 hour. If this is the only mod you plan on doing then the 3.5″ pulley should be used. The stock belt can usually be used but we recommend the 4060658 belt or our oversized tensioner pulley. The 3.5″ pulley swap will give you ~20 additional HP.  2004+ Grand Prix (Series III) supercharged cars will require  colder Tstat, colder spark plugs, cold air intake, TB spacer, and bolt in ZZP downpipe and that will just allow you to run a 3.6″ pulley.

Series II – If you plan on doing other modifications as well then the 3.4″ pulley is a better choice. It requires a smaller belt or an oversized tensioner pulley. The 3.4 will give ~25 additional HP. Supporting mods that are required include colder Tstat, stage 1 throttle body, colder spark plugs, cold air intake, TB spacer, we recommend at minimum installing the Ubend delete, but the best exhaust mod is our downpipe.  For additional exhaust flow, you could look into our stainless Powerlog.

Available octane plays a part as well. If you live in a state with only 91 octane available you will need to do additional mods to run a 3.4″ pulley without KR. You might want to consider the 3.5. If you live in Indiana or parts of the country with 94 or 95 octane available, it will be very easy to run the 3.4 pulley w/o KR. Keep in mind that a larger pulley with no KR will make more HP than a smaller with less timing (more KR).

If you plan on continuing to mod your 3800 in the future you should buy our modular pulley system. The assembly is lighter than a press on but more importantly, it will make future pulley swaps easy without needing to use the puller tool again. Then as you mod your car, you can buy smaller pulleys. This will allow you to run one size pulley for the street and one for the track or when using race gas.

After or along with the pulley you should run a colder Thermostat and colder spark plugs. The 160 is the best choice but doesn’t work very well in winter operation. You can switch back to stock for winter use or buy the 180 and use it year round (99+ cars should use a 180* thermostat to prevent CELs, unless running our ZZP 1.0 pcm).

For a colder spark plug we recommend the NGK TR6 or TR6ix. These plugs will help to lower KR. New plugs will also increase the performance and gas mileage of a car with used plugs. Many people run TR55’s but we have found no ill effects of running TR6’s and they work better for getting rid of KR.

If you have a 97 or 98 then a CAI is a very good choice as your next mod. If you have a 99 or newer your air-box is a little better and you can postpone doing a cold air intake if you install a drop in K&N filter. The ZZP 3800 cold air intake will give excellent gains and help reduce the KR that you will most likely be getting from running the smaller pulley.

Exhaust should be considered at this point. The bolt in downpipe should be your first part of the exhaust to upgrade followed by removing the resonator. After that you can replace your front exhaust manifold with our Powerlog and next would be a ported rear manifold. The factory mufflers are not restrictive and should be changed based on looks/weight/sound before all else. Once you’re making over 300WHP then we can talk about the performance aspect of a cat-back exhaust. The U-bend and/or resonator should cost $50-100 to be replaced by a local exhaust shop. You’ll want to pick up an O2 simulator if you are planning on eliminating your rear O2 sensor. And yes, this stuff is all emissions legal as you are not messing with the operation of the cat. Exhaust work is an excellent way to get rid of KR when running smaller pulleys.

Easy mods from here include a water pump under-drive pulley, and a throttle body spacer. The Spacer will help get rid of KR, the WP UD pulley will free up a few top end HP. Both are inexpensive ways to continue the pursuit of more HP.

The ZZP PCM is an excellent mod a this point. It will help lower KR, and make driving the car a much more pleasurable experience. It increases HP, changes shift points as well as fueling, makes the car shift harder under Perf shift mode, takes away your top speed limiter, raises your rev limiter and has a few other tweaks. It will lower your gas mileage slightly and increase the chance of tranny failure (due to firmer shifts) but at your HP level now you shouldn’t have to worry about the transmission yet.

At some point above you are going to want to consider Poly Motor Mounts and a shift kit. The shift kit in combination with the PCM can break hard parts in the transmission so that is something to be aware of especially if you have heavier rims/tires/brake rotors than stock.

You are now done with the easy stuff that most people do. From here you need to decide how far you’re going to take your car. This will help you make the decision between high ratio rockers and an after-market camshaft. If you plan on being faster than mid 13’s or make more than 280 crank HP you’re going to need to do one of 3 mods. Rockers, intercooler, or Cam. Rockers add ~25HP, increase gas mileage, do not change reliability of the car, cannot be seen by the dealer, are relatively easy to install yourself and will support low 13’s without an intercooler. They help the engine flow better, lowering KR and allowing a drop in pulley size by about .1.

Combined with an intercooler many users have taken a 3800 with stock camshaft, rockers and an intercooler deep into the 12’s with close to 300WHP. Bang for the buck rockers are an awesome mod.

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52 Responses to How to Begin Mods to Your 3800 powered car

  1. Caleb says:

    I have a 98 Grand Prix GTP with about 178,000 miles on it. I was wondering is it worth adding mods to a engine with that many miles, and if so where should I start with the mods? Or is it better for me to just get another engine, and start from there?

    • Zoom says:

      Most motors that age are worn out. However, if it’s had synthetic oil it’s entire life, it will be fine for upgrading.
      Level 1 performance stuff is a 3.4″ pulley with smaller belt, colder plugs, colder Tstat, Wizair box, ZZP 1.0 PCM and Ubend delete in the exhaust. This will drop you to about 14.0 in the 1/4 depending on traction (13.8-14.3). It will bring you from 240HP to ~285HP and make a large seat of the pants difference. No transmission upgrades are needed, reliability and gas mileage are not affected. To maximize the level 1 stuff, you can add a stage 1 throttle body, water pump underdrive pulley, power log, or throttle body spacer. This would add another 10HP or so and give more consistent performance. The stage 1 throttle body improves throttle response so the ‘feel’ of the car is changed. The downpipe does the cat and Ubend as well so you could scratch that from the earlier list. These modifications do not change gas mileage. 93 octane is recommended and 91 minimum is required. You don’t need any additional coolers or other parts than listed above.

      • Caleb says:

        But it hasn’t had synthetic oil all its life. I guess my thing is should I have it rebuilt or just get another engine just like it put in and mod that one out. I’m trying to figure out the best option and lease expensive one also. I don’t want to start modding my engine that has 176,00 miles on it and then engine itself really cant withstand the new modifications. Like I love ZZP long block engine although its a little pricey, I just need to be pointed in the right direction, so I know what I need to do and where to start.

      • BIGG.E says:

        im looking to purchase a 99 regal and sleep it but i refuse to put the money outside the engine with over 100 thousand miles. i plan an entire overhall. besides the add ons and bolt ons what are the options for the not playing wit em at all. i got some so egos i need to crush so bad

  2. Joe says:

    I noticed beside the log there was no mention of headers why not? How does the throttle body increase power?


    • Rob Estes says:

      Larger diameter throttle body means more air coming in. Big breath in means you need to get a larger diameter exhaust once you start to really get into these modification, engines also need to be able to exhale fairly well to take advantage of the increase in intake volume.

  3. Edward McSwain says:

    I just wanted to thank you for having such an amazing line of performance products. Its pretty much a one stop shop for all my needs in order to begin modding my 05′ GTP and your instructions and descriptions in your catalog is extremely informative and helpful.

  4. Tanner Cummings says:

    hello i have a 2000 pontiac grand prix gtp i recently just put your 3.5 modular pulley system on and an aftermarket intake and my check engine light came on 2 days later is this bad my car is completely stock other than the mods stated above the miles on the car are 149,000 i was reading and it said its safe to run 3.5 pulley on a stock car without changing anything but requires 91 octane.

  5. brian says:

    the comment above about the engine being worn out with 178000 on it is totally false without opening it up and looking at it for yourself. I personally have a 1997 gtp with (at the time 215000) and have torn it down under the same assumtion. I was in shock when I tore it all the way down and found the factory crosshatching still present in the cylinder walls not to mention no play in any bearings above factory specs and all seals and rings are still in proper working order with no signs of failure. Now if that isnt just a statement to the factory building of these rock solid “6 bangers” then I dont know what is. The engine I own still pulls super hard and shows no sign of age when “tickling the throttle body with my toes” , not to mention giving the “hemis” a good run for their money with a 17 year old car with now 235000 on the clock! And those hemis are not 5.7’s they are the 6.1’s in the “badazz” cars they are supose to be building these days. I sa y if you want to build something build what you got and when its maxed out go to something new dont just jump the gun and overlook the prize you have inside the wheel wells of that Pontiac!

    • zach B says:

      Hey I bought my car a couple years ago as my first car with 173000 on the clock and it now has 212000 the engine seems to run and pull fine It does have a slight tick but nothing serious but my trams seems to make some funny noises but it runs amd shifts fine did you ever run into that?

  6. Zac says:

    If i top swapped my l36 and install a intercooler, thermostat, and a downpipe what size pulley could i run?

  7. lilbeast1228 says:

    i have an 01 grand prix gtp with 95k on it and is clean inside and out motor looks almost new what mods u recommend since i have a limited budget

  8. lilbeast1228 says:

    how much torque and horsepower gains am i looking at if i do the stage 1 kit with the 3.4 pulley,intercooler,stage 1 throttle body, zzp downpipe,and the colder plugs and thermostat and slp exhaust

  9. 03 DOUG GTP says:

    My 03 gtp has real bad front end shake when excelerating,you throw it in neautral it stop,s. Had it scanned they said maf sensor thats not what it was everything is tight on the front end wheel bearings motor mount,,s drive axle,s. Any info would be Great…

    • Chris C says:

      I recently owned and loved my 04 GP GT at 120,000 miles, the issue you described was nearly identical…the issue being the outer CV joints…try to notice if this vibration is worsened with other people in your car (more weight = more pressure, which means more vibration)…if so, this is most likely your problem. Having said that i now own an 06 GT S/C with 101,000 miles on it, and the CV axles has grease leaking out of it everywhere, quite noticeable behind the (hidden) PS pump…Lastly, can you hear a popping noise of any kind when turning sharply, if so this is the Inner CV joint(s). it seems from 04-06 the GM CV axles were not of good quality, or perhaps i just had the worst luck lol…Good luck to you though!

    • Jon says:

      check your half shaft they have c clips that hold them inside the trans that often come lose

    • steve says:

      Had the same problem . Check you axles. I bet the passenger side cv joint is shot, probably the boot clamp came off..

    • steve says:

      well when was the last time u’v changed the spark plugs? u cud also have bad tires or air leakin from some where. I wud start with tune up if u already haven’t an maybe switchin front tires. as long as tie-rods an everything is tight start there.

    • steve says:

      check your lower ball joints my 97 buick riviera had the same shake and i found out it was the ball joint also keep in mind just because the cv axles appear to be good doesnt mean they are check ball joints if they are good look into the cv axles.

  10. Richard says:

    I have a 2004 gtp comp G I’m wanting to run the 3.4″. I live in Indiana so I get the high octane gas. Right now I’m running a downpipe res. and muffler delete, 180* t-stat, K&N CAI, high ratio rockers, and TR6 spark plugs. Am i safe to run the 3.4″ pulley???

  11. Jason says:

    Hi I have a 2003 head prix gtp with 98000 miles on it. I currently have the air box taken off and just a k&n filter attached there to get more air. Other then that this car is stock (to my knowledge) what more can I do without blowing it up or Breslin down my engine I want to keep the car but I’d like to have more power so these people in there Honda civics stop thinking heh can beat my on the track. I could spend around 2000 to put uno the car. Also I have a 3″ magnifier exhost I recently put on.

  12. jonathan baker says:

    hey i have a 2002 impala with the 3.4L i was wanting to swap for the 3.8 that you guys make… is that something i can do myself or do you have to change all the wiring computer ect…. basically i own the car don’t want payments on another one but want more power i figure i can put 10 15k into this one and have a brand new car… any suggestions help thanks

  13. GM Man says:

    I live in California an have a 2000 GTP with 171,000 miles the lady that owned it before me had the engine replaced at 135,000 miles the replacement engine had 43,000 miles so I have about 80,000 miles on it. I wanted to know how far can I mod and still pass SMOG?

  14. Andrew says:

    My GTP has 187,000 miles and I could mod it tomorrow. It will still haul @$$. GO for it.

    Richard, yes, that would be fine.

  15. Skyler says:

    I have a 1999 Monte carlo with 142,000 on it, whats a good starting option to add some power while on a budget?

  16. chris says:

    i have a 98 regal gs with a L67 , my mods are magnaflow down pipe and cat with the zzp 1.0 pmc ecu, also k&n filter what else shold i do to it.

  17. Joseph says:

    I bought a 07 Grand prix GTP its bone stock with 84k miles. my best friend owns a 06 pontiac gto.I’m freaking sick of him kicking my butt. I have about $1,200 budget to work with and wanted to know what mods can i get to finally whoop him with that budget. Thanks a lot.

  18. J.Reyes254 says:

    hey I have a 1998 Riviera supercharged any tips on hp gains?

  19. Tom says:

    I have a 2006 grand prix gt, 91000 miles. What mods would you recommend for a daily driver? I would like to get a little more out it, but nothing radical as I do daily drive it. What kind of gains can I expect.

  20. Howdy very cool website!! Guy .. Beautiful .. Amazing .. I will bookmark your blog and take the feeds also?I am glad to seek out a lot of useful information right here within the put up, we need develop more strategies in this regard, thank you for sharing. . . . . .

  21. John says:

    I have a 1998 GTP with a little over 170,000 miles on it. I was just looking for suggestions on light mods. I know my model year has a poorly breathable airbox. So I was considering buying your zzp cold air intake, but I also am looking at a high flow catback. If I do both of these they won’t be at the same time, so which would be best to get first. I don’t feel like making mods to the supercharger or the engine itself. I’m also open to a downpipe if that would help too. Thank you!

  22. GTP Freak says:

    I am planning to install a 3.4 pulley, if i take all the measures listed to reduce KR, colder plugs, tstat, cold air intake, and ubend delete, can i get away without replacing a pcm?

  23. I truly enjoy reading all the wonderful information on the 3800 series II, I personally own a 88 Fiero Formula, with 161k on the clock. the only mechanical work thus far, timing chain replaced at 125k, flex plate at 145k, new front hubs at 150k, and front end rebuild at 148k, rear end rebushioned with poly, as well as the front. I have replaced the A/C compressor with a new unit, instead of rebuilt at 160.5k, I had one rebuilt unit and one used unit prior to the latest install. I have new stainless GT exhaust tips, original muffler still. replaced the cat at 140k. I run Kelly GTs on stock rims. I repainted Dec. 2012 with the 2008 Pontiac Soltice Red. When I’m in need of a transplant I will no doubt do the 3800 s/c or turbo. I haven’t had no trans problems thus for. Keep up the good that you’re doing. thanks a million.

  24. Your information is very well put together, and informative. keep up the wonderful good that you are doing. I simply love it, even though I don’t have a 3800 yet!

  25. Andrew says:

    Ive got an ’02 GT and want to look into getting more power out of it. some are telling me to go ahead and do a top swap but are there any upgrades that can be done to the N/A gt to get a substantial power gain?

  26. Brad says:

    I have a 97 GTP looking for do some modds ever should i start!? Can anyone point me in the right direction

  27. clark says:

    I love Indiana and it’s 97 octane.

  28. jerry boardman says:

    Hey I have a 98 olds intrigue with a 3800 series II n/a it recently created a knock within itself. I know replacing it is my best bet but I was wondering if i could replace the stock engine with one outta a gtp or another similar type of vehicle to end up with a supercharger setup ?

  29. jeremy says:

    I was wondering if these products can work on a 2000 camaro 3.8 l v-6? Cause a lot of things I’m reading is about grand prix

  30. Jay says:

    I have a 2004 dalejr monte carlo with the 3800 series II supercharged engine. What mods should I do to compete with SRT8’s that are stock?

  31. Vincent China says:

    What about non s/c cars. I have a 2004 Impala LS. Where do I begin?

  32. Justin says:

    I know this is an old posting but here goes anyway…..which of these mods can one do to a N/A 3800 without having to run 91+ octane fuel? I know obviously CAI and exhaust, but what about HV3 & other engine mods? Is tune available for 87?

  33. GB3 says:

    I want to start upgrading my stock 2004 gtp I was thinking of starting with intercooler s2 or the stage 2 performance pack? Which one be best?


  34. Just bought a 1998 Grand Prix GTP and I want to drop down to a 3.4″/3.5″ pulley. But I don’t know where to start and could you make me a list of what I need to get done first down to the last. Cause I will be ordering from this website.

  35. HULK 2002 says:

    I have a 40th anniversary GP L36, I’m changing to be S/C.
    My mods are both ported blower and lower intake, ported manifold,
    ZZP downpipe, ZZP 180 Tstat, ZZP shift kit, ZZP torque converter,
    stage 1 L67 throttle body, throttle body spacer, ZZP fuel log, ZZP inter-
    cooler kit, K&N CAI, ZZP wires, ZZP pcm, and XP CAM.
    My car is at 157,000 miles. What other modes do you recommend???????

  36. Matt says:

    I have a 2000 Buick Lesabre 3800 l36 NA. I think she has about 170,000 on it and was wondering what i could do to put a little more fire in her heart. everything runs perfect, and the tranny is dam near new. You mention alot of things but do they apply to the NA or just the supercharged ones?

  37. rick says:

    what is this ‘kr’ they keep mentioning????….they say it over and over like i ‘know’ wtf it means???…lil help, plz? (i have a 2000 gtp in my shop w/ ’05 motor. appears to be modified, but owner bought it that way, so i ‘dont’ know for sure whats been down, it has a spacer,u/d pully, ‘mod/ecu’,differnt exh.,flow thru cats, etc…)

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