Hey guys i’m starting my second build. I’m going to be running aluminum heads stage 2 from ZZP, GEN five supercharger with a ported inlet of 102mm for a 102mm throttlebody, fully ported manifold, stage 2 intercooler, 2.6 pulley, je forged pistons bored .20 over since I’m boreing the block .20 over 9:9:1 compression, e85 and currently have an xpz cam with 1.65 rockers. I have a custom fuel system -8an and -6 return 80# injectors and so on. I’m stuck between running my xpz cam or getting the is4 cam from intense. I want to make the most power on my build and as you can see I’m going all out on it. I don’t care about driveability but mainly performance. Anybody swap from an xpz to an is4? And input would help! Thanks-Zack

 

Curious, have you seen anyone actually do this with positive results?

I totally understand that less restriction in front of a PD blower yields better efficiency, the downside is that the hole going over top of the rotor bearings is only so big, even ported. Eventually you hit a point where bigger wont yield more power because it hits a choke point anyways elsewhere (inside the blower). I dont recall seeing any gains from the 90mm TB a few have done over the common N*, so I wouldn't think going even bigger would be a good thing.

There is a downside to going too big as well. You end up with a lot of less ability for throttle modulation. You'll end up hitting a certain % of throttle opening that acts like WOT as will every TP% past that. Also the cheap TBs with a straight bore and regular round pulley can be touchy to drive as so much air can get in with so little throttle. Keep in mind that this shift to crazy huge TBs didn't really come into play on the V8 side until electronic TBs were common. That allowed you to map a large range of pedal position to a small amount of actual blade opening so you still had good control.

I guess my point is that I'd run the smallest TB you can without impacting power. I've probably got the only 102mm TB 3800 on this forum, but I've also got a much bigger blower.

A couple things on this one:
-No reason to run forged pistons on a SC setup, stock pistons have proven to easily handle the 400ish whp a maxed out M90 can make. It's literally just money down the toilet. If you want high compression, L36 pistons and shaved heads will get you close.

-i wouldn't do .020" over either if you do need to replace the pistons. Only bore it enough to clean it up. There is very little displacement to be gained with an over bore on a 3800 (and hence virtually no power). On the flip side, thinner cylinder walls will flex more and give worse ring seal making for less power when pushed. I'm not saying .020" is enough to cause notable issues but unless you ultrasound the block first, you've got no idea how much core shift it has and would really just be hoping it works ok. IMO the risk isnt worth the negligible reward. If you're really after more displacement via bore, do it right and sleeve it IMO.

If it really is an "all out" drag build, have a custom cam specd out for your exact setup.

If I had to pick between the 2 for an M90, I'd go XPZ. History speaks for itself, the XPZ has made notably more power on the M90. IMO the IS4 is too big for the M90. Neither has drivability issues. The IS4 is a bit rougher, but you could literally DD either with the right converter and a good tune.


On a side note - I'm sure you're aware, but in case you aren't - even if you set a M90 record, you'll never get turbo power numbers. With a 2.6", the M90 is way beyond its intended efficiency range and even with fully maxed out everything, a fairly basic turbo setup will easily make more (and for a lot less money). Just didn't want you to dump $10k into it and be disappointed the first time it gets walked by relatively mild turbo car.

 

Yes I understand that. I would buy the 140ax whipple but I don’t know anyone who can make an intake manifold or adapter for it to work with my stage 2 ic core and manifold itself. If you know anyone let me know. This 3800 will never see a turbo, if I buy another than I will.

 

One of the downsides to the 3800 typical group (not saying this forum, just in general) is that they like to make it sound like adding an aftermarket blower is some kind of black magic voodoo. A handful of people struggled with a single poorly designed kit and that snowballed into making it sound like adding an aftermarket blower is so difficult. It's really not rocket science to install whatever blower you want.

The other limiting factor is that few people want to put lots of money into the 3800s anymore. But if you've got the spare cash for ported aluminum heads and a rebuilt/ forged bottom end, custom blower adapter parts aren't really that expensive.

I offer 2 options for a 140AX:
-If you're ok switching intercooler, Yella Terra makes a bolt on setup. You can buy their lower adapter / IC, their snout, and their 8 rib pullies (they have a huge selection down to absurdly tiny). It all bolts right on. Only downside I see is that the intercooler core is on the smaller size. That's easily remedied by adding a spacer plate to the center of the sandwich to allow you to run whatever thickness IC core you want (personally, I went with a 3").

-If you're dead set on keeping the S2 IC, youd need an adapter like the old Animul setup - where it was literally just a bolt pattern adapter plate. Any good machine shop cam easily make this. Youd just have to take in (or send off) your LIM and the blower case and tell them where you want the blower positioned on the LIM (for belt alignment) and they'll machine you an adapter out of aluminum. It's pretty easy work for a good machine shop.

 

So the yella terra whipple kit will directly bolt onto my intake manifold? And what website can I find this kit? Yellaterra.com? If that’s the website, I tried purchasing the kit but it didn’t give me the add to cart option. That will definitely work with an l36 converted to an l67 set up?

 

The lower adapter bolts right to the L67 LIM and the snout lines up with the 8 rib ATI balancer.

You need to call or email them, you don't want to buy the whole kit. You wont need the extra IC parts or the inlet adapter.

The only L36 part will be the bottom end, get your aluminum heads drilled for injectors and put on a L67 LIM. Nothing L36 will be mating to the blower.

 

So all I need is the blower, intercooler and balancer. and what else? Also it looks like on their Facebook that the kit is discontinued and they are making a new one. I emailed them just now. Wonder what the shipping cost is oh boy lol

 

I sent them an email. I tried creating account but I keep getting a captcha message so it won’t let me. Seems like there is a new whipple kit coming out that may be why I can not add this one to cart. Definitely going to get it once it’s out just have to figure out how to make an account so I can purchase it

 

From Yella Terra? All you need from them is the lower adapter / IC, snout, and whatever pullies you want. I suppose you could buy the blower from them too, but I'd definitely shop it local first to get an idea what they go for. I'd guess you could probably find it cheaper over here.

I wouldn't worry too much about shipping, especially if you dont buy the blower from them. Main reason I say that is the exchange rate is awful for them right now. Last I looked it was nearly 1 USD to 1.5 AUD, so you're going to be paying much lower prices than what you see on the kit and such.

 

No reason to make an account at all, you wont be buying anything through their website, just via phone or email. Unless you plan on buying the whole kit for whatever reason, their website isn't set up to sell individual pieces.


2 other things to mention:

1.) I'd take a look at the balancer you were going to run with the M90 2.6" to make sure the ribs are extra ribs are added in the same place as the ATI / whatever balancer YT sells. You'll need to figure out what you're going to do about the IC - either run it as is or have a center spacer and bigger core custom made. IIRC the stock YT core was only like 1.25" thick. Probably not as big of a deal on E85, but youd want more for max effort.

You'll need to figure out what to do about an inlet to mate up that 102mm TB. Obviously the YT piece is going the wrong way due to RWD so that's out. I see 3 viable options today A) contact PRJ and get another cast adapter (I want to say it was only 90mm though and was like $1k by the time they got done with it). B) call up Whipple and see what adapters theyve got that mate a LS 102 to the whipple; last I looked, their usable options were classified under sand rail applications. C) Have your own made. This is the route I went so I could specify exact sizes, positioning, port placement, etc.

Lastly, you'll need to figure out a plan for the BBV. I just bought the Whipple one and incorporated a spot to bolt the flange for it into my design for my TB adapter. There are options from other brands that are in line with hose connections on both ends if that's easier too.


2.) Just to be 100% upfront, I'm not at all suggesting this route as a smart way to go. It's not an easy route to go, and there is near zero tech support out there. It still likely wont make as much power as the best 3800 turbo setups and its going to be stupid expensive (especially given all the other high dollar stuff you were looking at). By the time you add up the cost of all these parts (including a GMR trans to hold the power), you could literally buy a C6 vette (or a C5 + a blower kit). I'm just offering the advice about this route as you seemed interested and I've already been down the path so I'm sharing what I've learned.