fixed lol. Listen man I hopped on the bandwagon too with the same heads as you just admit it we assumed that just because it said LS7 it meant all LS7 type heads. Problem is that now you have a $5k manifold and your still in the same boat.

 

Nah its going to be alot easier to fix compared to the fast as its metal there is so many options to fix it.

1. make adaptor plate spacers see if that works
2. fill in bolt holes on the manifol and tap new bolt holes
3. cut flange off manifold cnc cut a new flange with the right bolt hole locations to suit my heads

the port sizes are correct and the port spacing is correct i have measured my heads and i got harrop to measure their intake for me so its going to be a good port match but obviously the bolt holes "might" suit LS7 and not LSX.


It's a shame really i feel there is a trickery here from gmpp cause they have everyone convinced its just a better version of the ls7 head so people like you me and the many others out there think we can just buy an ls7 manifold or a fast ls7 manifold.....hell even GMPP has an LSX454 in their catalog with an LS7 manifold on it and what about denoyeer building the camaro with the 454 they too think they can bolt a fast 102 up to it, it is 150% a mistake gmpp has made.

Look at the front cover of their catalog the LSX454 with an LS7 manifold sitting right there ontop

 

Just curious which solution are you leaning toward. I would think that filling the wholes and making new ones would def be the best solution but I don't know if it would be the easiest do to manifold design.

That picture is misleading too because the 620hp model is the carb version and yet they show the EFI version with like you said a stock ls7 intake.

 

well i have a bare head to work from which is exactly the same cnc'ed heads i have on my car, i think i'll first make up a template and then make up a program and laser cut out some 6mm plate and then bolt that up and see how it looks, if thats all that is needed then great, if not i will look at filling the bolt holes on the manifold and then re drilling/tapping new holes to suit.
i want a perfect fit and yeah even when i get it i might do some hand porting to get that perfect fit.

i got the port height/width and port spacing from harrop and based on their measurements and mine its going to be a very close fit.

Measurements are:

Harrop
port width 31.41mm
port height 58.84mm
port spacing 80.4mm
(gasket porting area from inside port to gasket)
left side 4.8mm
right side 2.4mm

LSX LS7 Head (cnc ported)
port width 34.5mm
port height 59.1mm
port spacing 78mm

As you can see its very close not perfect but very close, it might not even be worth a tidy up and if i get it and its completly wrong i'll just send it back and look at building my own sheet metal if im forced to, or a friend of mine is doing itb's i'll just get custom ones that will 100% match up as we will make the flanges ourselves.

Just like the corvette Z06 brakes i now have fitted to the GTO...lol custom brackets made from 7071.

 

You are unable to read. Period. I have the same heads as you do!!! What the hell do you not understand when you read that sentence. The fast 102 intake bolts up without any problems to the as cast gmpp lsx ls7 heads. I personally built this engine last January. I cleaned up the ports on the as cast heads and port matched the intake to the heads. Car produced 602 rwhp in corvette. BTW I have visited Australia and think you folks are a great lot. Also thought you might be wiser than this.

 

thanks i have listened but have had 2 different shops here tell me they have had the same problem with the LSX heads now and that the fast 102 bolts up perfectly to the LS7 head but not the LSX head.

What more can i say.....

 

Did you get the ITB manifold yet I'm curious to see how far off it is if it's off?

 

I have been in contact with harrop and i have sent a bare LSX LS7 head to them so that they can chop/cut/adjust the bolt hole locations on their manifold if it is needed before i fit it.

 

Good idea. Least they could do for 5k lol

 

$225 elbow $427 intake manifold $400 to get the injector bungs drilles out and the manifold tapped brings the total to $1052 throw a NW102 tb in for $600 and you have one badass LS7 intake setup olif I do say so myself..

 

this wont clear the hood though?

 

I have a Trail Blazer SS but you car guys would just get the lower profile elbow and you should be good. I know a lot of guys cut the cowl underneath or what not. The intake itself puts the flange only slightly higher than the heads hieght. eddlebrock makes a black elbow that is like VERY low pro that I know would fit if you really wanted to be sure you could use this setup.

Here's the car elbow like mine
http://www.6061.com/lsx.htm

Here's the eddlebrock elbow
http://www.edelbrock.com/automotive_...e_elbows.shtml

 

Dont the low pro elbows limit flow?

 

Depends on the elbow and setup but it is true that a taller more direct elbow would flow more. If your dead set on every last bit of hp you can go with a cowl hood or cut the stock hood to clear a taller elbow but I would go with a lower pro elbow. Or you can always get a 4150 tb which bolts right to the manifold and you put a air filter on top like you would do with a carb setup.

Here is a 4150 tb
http://www.summitracing.com/parts/FST-304149/

 

ok i have the harrop intake in and i have great news.

harrop measured an LS7 head for me in all possibly ways where the bolt holes are located in relation to the ports, they then measured my LSX LS7 head and got the exact same measurement other than my ports were the slightest bit larger due to cnc porting.

They then bolted the intake to an LS7 head looked inside and it matched up fine, they then bolted it to my LSX LS7 head and looked inside and it matched up fine.

Then once i got the manifold as i would like to see this "matched up perfectly" thing myself i bolted to my LSX LS7 head and yeah its a near perfect match i have attached a photo its very hard to see but it does match up very nicely.

So i still think the FAST manifold is a piece of ****....lol

 

Man just let it go why you so head strong on bashing a company. First it's F.A.S.T then it's GMPP now it's F.A.S.T again. FIrst off who says that Harrop even knows what they're measuring or that their measurments are right? GMPP makes two different intakes one is just for the LS7 head the other is for the LSX LS7 head so obviously there is a difference. You got a intake that wasn't for your heads that's all. Enjoy your new intake and just keepon going faster.

 

Looks good O.N. Get that thing on and tuned. You should be in for a nice gain in mph. The Harrop is a nice piece. I'm assuming you are staying dbw?

 

Well no you are bashing GMPP and sticking up for FAST.
The LSX LS7 head is suppose to be an "as a cast version" of the LS7 head with only 2 additions a thicker deck and a 6th head bolt.

Harrop are not dumb so don't assume that they are. They are one of the industry leaders here and they make some very good products and have been doing so for the last 75years also with their involvement in V8 Supercars.

If they have measured both heads and gone to the trouble to get me to send them my LSX head then they have measured both heads, they also built their intake from the measurements of the LS7 head so the intake they built is built to match up with the LS7 head.

Now the intake i have from them matches up fine in their shop on an LS7 head and on my LSX LS7 head, and then when i got both sent back to me i matched them up fine too.

The only manifold in this situation that doesn't line up is the fast manifold.

GMPP even states in their catalogue with the picture of an LS7 manifold on top of the LSX454. The heads are as cast LS7 and the measurements harrop have taken were the same and the manifold they have built lines up near perfect on both LSX LS7 and LS7.

I am not harping on about it i couldn't give a **** anymore but what i do care about is other people should take the time to see how the fast fits on their LS7 heads or their LSX LS7 heads. Personally if i had of not ported the fast manifold and had of tried to only install the lower shell when i very first got the fast manifold i would have sent the thing straight back unused and got a refund.

End of rant i have supplied pics of both the fast and its problems and i have supplied the pics of the harrop as best as i can and it's near perfect match.
I have made harrop fit the manifold to both my LSX heads and the LS7 head i have made them measure all bolt hole locations and even had them completly understanding my problem with the fast and willing to help me if i had the same problem with their manifold by cutting/welding/adaptor plates/etc to make it fit. Luckily none of this was needed and it matches up fine.

Best of luck to whoever buys a FAST for an LS7 style head i'll never buy a fast again or recommend it.

 

Im glad your happy with your new intake but if the company that makes the head says there is a need for a different manifold Ill take that over a 3rd party company who makes parta for it. Too many people using porting and messing with them for it not to be a isolated problem to either aftermarket heads or just a bad bottom. Either way all's well that ends well.

 

well no GMPP have not said there is a need for a different manifold at all, they have said we have built a carb style manifold and you can run that intake or the ls7 intake hence the photo on the front cover of their magazine displaying the LS7 intake sitting on top of the LSX454.

Its a FAST **** up plain and simple.

see picture where it says ls7 style port.


Also see this picture where it says suits only LS7 and LSX LS7 heads.