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Z3 vs Top Swap for DD GT

brettstoner

brettstoner

New member
I have an 04 GP GT, 80k miles, stock engine, Impala front brake upgrade, and a TEP trans on the way. Plan on doing some front suspension work when I drop the trans next month. Car is a daily driver, kid hauler, all-season tires, and not a tire burner or track runner.

I am looking for more power and have it narrowed down to either the Z3 turbo kit from ZZP or a top swap (w/ headers, rockers, 180*, tune). Cost wise the Z3 intercooled kit will run me around $3.4k and a top swap $1.2k ($500 used parts, $200 headers, $100 cat, $100 powdercoating, $125 tune, $100 gaskets, bolts, etc)

For a daily driver on street tires is it worth it to spend double or triple the amount for the turbo kit? From a performance standpoint a turbo is a no-brainer but I have no intentions of future mods once I am done now. I am looking for an upgrade from a stock GT and a top swap is so much cheaper.

I am wondering if traction is going to be my limiting factor? If I end up with a tire burner just with a top swap then I don't think the turbo kit would be worthwhile with traction being the limiting factor. Am I off base? Why spend an additional $2k just to see 1st gear go up in tire smoke and always fighting traction? I like fast acceleration not tire smoke shows.

So I am hoping those with a budget turbo upgrade or bolt-on mods on the M90 V can comment on the differences? Is it worth it to spend the cash knowing no future upgrades? Are you always fighting getting traction or really have to modulate the go fast pedal? What about in OH/MI snow/ice winters?

HP/TQ is nothing if you can't put it to the pavement. I don't mind upgrading to high performance all seasons but slicks or dry season tires are a no. It is a DD.

I appreciate the guidance.

Thanks,
Brett
 


a factory supercharged gtp has traction issues. I think if you did the top swap with a cam you would be very happy with the power and not be over the top with money spent.

another option is to look around for a used turbo kit. ive seen them go for 1500.
 
Thanks for the input. A 50 extra HP makes no difference if you can't put it down! I have thought about a mild cam vs rockers with the top swap. If I go top swap instead of turbo I will read up more on it.

I also hate how our traction control pulls a ton of timing so the motor falls on its face. It is more a nanny control then a launch control. I like the racelogic traction control but it is pricy and discontinued.
 
Also something too I am keeping in mind is MPG. Since it is a DD I don't want to kill the MPG. I get around 22-24 city, 30 highway right now.
 
a good tune will adjust the traction control, which you will need to maximize the benefits of either a top swap or a turbo build. in my opinion, when doing the top swap, you have to take the harmonic balancer off to replace with a supercharged version, and it isn't much more work to change the cam once you have it off, I don't think gas mileage is much different with a cam, unless you go full throttle a lot. I would suggest either an XP cam or an S1X
 


I loved the vs cam, good all around power for dd use. 1.7 rockers set the vs cam up nicely too.

In either case you'll want to replace the timing chain and dampener. So you might as well throw a cam in for few more bucks.

Turbo will keep your mpg up and is a ton of fun. You already have the trans so you could go with the z7 or cartuning kit for some more power. I top swapped first with headers rockers, etc and it wasn't enough power for me, and then I went through all kinds of builds. Turbo was my favorite hands down, I'm even throwing a z3 kit on my impala that I didn't plan to mod lol. I'll always turbo or get a turbo car from the factory.
 
What differences where there driving the ZZP VS cam vs turbo? Besides more power? Was the power linear? More mid-range or across the board power? Stronger pull at top end? Trouble trying to hook off the line?

Well I ended up getting a fantastic deal picking up a used 04 GTP motor this weekend. Sealed the deal for a top swap. So I am looking at a top swap, headers, VS cam, HAI, and usual compliments for such setup. Going to get ZZP to do a dyno tune and help figure out pulley size on 93.

If I wouldn't have gotten the top swap so cheap I was leaning towards the Z3 turbo setup.

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Your advice mirrors all my research so far. VS cam for a mild build. XP for a step up with better springs, double roller, and higher rpm HP. Still very streetable.

I plan on going VS cam, new stock chain and dampener, 90 springs with seals, retainers, and locks. Clean up castings on the heads, intake, supercharger, tb when necessary. No porting. AL104 plugs, 180 tstat, EBay headers, Magna flow high efficiency cat, stock injectors cleaned, stock cat back, and cone filter the MAF.

Get a mail order ZZP tune til I can run up there and do a dyno and pulley size.

Merry Christmas to me! It will be a busy Christmas vac for me!

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you could gasket match the inlets on the heads and do a light porting.

There is a guy that does tuning in coldwater ohio, which I would imagine is a lot closer than zzp, and he will charge you a lot less than zzp. I am sure he will do a good street tune for you
 


If the bottom end of the gtp engine is good then you should use that. The l26 pistons can pop because the piston rings can't expand like the need to, or something like that, when power is added.
 
While that motor is out I would bet your going to dress it up and make it look nice so while your at it get a set of custom valve covers pm me or search my name check out my shop

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Several things...
I am not interested in custom valve covers. They don't make me go faster. That would be better served in a PM to me.

Good idea on port matching tb, charger, intake, heads. Will do!

Unknown condition on bottom end of GTP. Going to stick with L26. Low miles, higher compression with the top swap. Hoping with VS cam, headers, and intake I can run a 3.5 pulley on 93. (Gen V and higher compression of top swap)

Can you send me the name of the shop you are referring to in Coldwater? ZZP is 3 hrs away. Intense Racing is 2 hrs. I don't have personal experience with either one to decide. I am down for any reputable tuner on a dyno.
 
Of all the 3800 blocks, the L26 is the most prone to failure. The guy I'm referring to doesn't have a shop, just does tuning in the side. I would be more likely to go to intense instead of zzp
 
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