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Does LPE or TPiS still offer the 90mm snout on the OEM LS6?
Thanks
Happy to share.
In roughly November of 2017 LPE still offered the 90mm snout modification for an LS6 intake. I don't know if it is still offered. I've had one on my 91 RS for several years no issues. Still happy with it but if the car gets a bigger cam it will be Fast time.
The LS6 intake runner well ported (rare) will max out around 275 cfm so in theory max is about 600 flywheel hp. A ported Fast 92 runner can do about 285 cfm in theory so max about 630 flywheel hp.
Its hard to argue with picking up a good used Fast 92.
Subscribed to thread.
Black Bird T/A thank you for this invaluable information on cathedral intakes. Today I went through the whole thread again.
I am sorting out parts for my low mileage street only LS1. I will use TR224/227 cam and ARH 1 7/8 headers/catted Y-pipe/3 inch exhaust.
I am unsure what heads to use, I have a choice of big port 862 heads with 2.055 Ferrera valves that are probably overkill for my application or stock Z06 243 heads with lightweight valves that will hurt power.
I planned using my stock LS6 intake and stock ported/epoxied/polished throttle body, but after seeing flow numbers of 90mm TPIS/LPE LS6, I’m thinking of sending my intake for 90mm snout replacement.
Attached are pics of my ported 862s. Let me know what you think about this intake port for my setup. Apologies for getting a little off topic.
You might want to compare the cost of converting the LS6 to the cost of a Dorman LS2 manifold. The Dorman is VERY reasonable, and the snout conversion is not cheap.
Just FYI
Dorman LS2 is a good alternative, there is extra $$$ needed to cover for supporting accessories to work on LS1 in f body as mentioned by WS6Store early in the thread. Not sure how much more.
I’m also strongly considering Fast 92: more power for more $$$, however I’m afraid it won’t have LS6 good driveability.
Quality and good street manners are my top priority. Hacked and epoxied snout is not what I consider quality. Anybody ever had issue with 90mm snout on LS6 intake?
I’m debating between TPIS 90mm LS6 or FAST92.
I'd go for the TPIS 90mm LS6 personally. For the same reason: good driveability and tuneability. Had a stock LS6 intake with a huge cam (MS4) in my LS1 CETA. Drove like sh*t when I bought it but was quite easy to tame with a wideband, HP Tuners and a little patience. I'd sacrifice a few hp for easier tuneablity and hence driveability anyday.
Cino, your 862 heads look pretty sweet with the port work. I think they should make good power. Have they been milled any?
The Dorman LS2 is ok, but i would much prefer an Fast 90/92 or an TPIS LS6 90mm based on my experience with all three intakes. The Fast 90/92 will drive decently good, but TPIS LS6 90mm was better on my 91 RS in power and driveabilty in my experience. The Dorman will cost more to adapt for cable TB.
Both of the TPIS LS6. 90 i have look professional they arent hack jobs. Dab of black paint for touch up on bolts if needed and your set.
No issues with the TPIS LS6 90 on my 91 RSxfor 10,000 + miles and 4 years
Your comments in this thread about driveability and power made by TPIS 90mm LS6 on 383 LS1 vs FAST intakes made me seriously consider sending my LS6 intake for 90mm snout replacement. My setup will be similar to yours, just a tiny bit milder.
What is the throttle body you are using on your LS6 intake? I want one that won’t give me headaches.
862 heads were not milled, but combustion chambers were machined to unshroud 2.055 intake valves, now chambers are bigger than original. I will have them cc’d and mill accordingly after I make sure I have enough piston to valve clearance.
They flow a little weak on exhaust unless they were flowed without a pipe.
I've read this thread from from to back (a few times lol). In that time I've probably learnt maybe half as much as Black Bird has forgotten when it comes to intake manifolds.
I had planned to do the TPIS ls6 mod for the consistent results it seemed to deliver, however after a few brews and some window shopping on eBay I found a fast 78 and the impulse purchase part of me got the better of me. Plus it could utilise my current 3 bolt DBW throttle body without the added expense of an X-link adaptor.
First thing I noticed is the ridges in the intake ports have been flattened (which I've heard is common), I'm no expert in airflow and I'm not real sure a photo would help anyone determine whether they've done a good job of it . So basically I'm in between having someone competent give it a mild 'clean up' or just sending it and hope for best .I'm kind of OCD when it comes to my car and dont mind waiting if I get the end result I want.
That grinded down ridges seem to be about the only 'porting' on the manifold.. Is there much else to be gained through further porting? - opening up the manifold to 85mm is off limits since I need to retain the 78mm throttle body.
The best thing to get flow is a good bowl blend and a good multiangle valve job. That and any cleaning up any casting zits and hiccups.
You talking about heads or manifolds here? 😝
So far all I've done is smoothed off the 90 degree corner in the mouth of the intake behind the throttle body which I've heard can cause a whistling due to turbulence.
Hi Bad346, thank you for reading this long long thread!
I will have a minor update next week. My 02 Z28 finally got the 90mm LS6 used in the flow testing installed along with headers.
I think the Fast 78 is a good intake. Plus much easier to get properly ported than say an LS6 or 90 LS6. The best plastic manifold porting I've tested and see was from Tony Mamo of Mamo Motorsports. I have Fast LSXR by Tony and its A++ good. I bet Tony could wake up that TB as well. Tony great to work with and talk too about your project. Highly recommended.
Also there are a couple of forum members that can do very good manifold porting. HioSSilver one of our ls1tech member had a badass bolt on LS6 engine with a Fast he ported himself. It's probably worth PMing him and seeing if he'd be up for doing a port job.
There some room in most TB's to do some porting. I test a ported LS1 TB Lingenfelter ported that was worth 3 whp on my Trans Am when it was a bolt on car.
Hi Bad346, thank you for reading this long long thread!
I will have a minor update next week. My 02 Z28 finally got the 90mm LS6 used in the flow testing installed along with headers.
I think the Fast 78 is a good intake. Plus much easier to get properly ported than say an LS6 or 90 LS6. The best plastic manifold porting I've tested and see was from Tony Mamo of Mamo Motorsports. I have Fast LSXR by Tony and its A++ good. I bet Tony could wake up that TB as well. Tony great to work with and talk too about your project. Highly recommended.
Also there are a couple of forum members that can do very good manifold porting. HioSSilver one of our ls1tech member had a badass bolt on LS6 engine with a Fast he ported himself. It's probably worth PMing him and seeing if he'd be up for doing a port job.
There some room in most TB's to do some porting. I test a ported LS1 TB Lingenfelter ported that was worth 3 whp on my Trans Am when it was a bolt on car.
Appreciate the reply Black Bird and believe me if I didn't live across the pond in Australia Mr. Mamo would be my number one choice.
Unfortunately we aren't blessed with as much options here I'm Australia. Enquiring about porting the throttle body a few shops said they couldn't do DBW, only cable.😑
I do have a guy in mind I'm yet to ask but had wanted him to do some head work for me on some 799s, kind of makes sense to just freight him the heads, intake and throttle body together when I can afford to. He doesn't flash around big cfm flow sheets but he has a long time in the game and I see the engines he builds seem to dominate in improved production car racing here so he has my confidence. 😁
Appreciate the reply Black Bird and believe me if I didn't live across the pond in Australia Mr. Mamo would be my number one choice.
Unfortunately we aren't blessed with as much options here I'm Australia. Enquiring about porting the throttle body a few shops said they couldn't do DBW, only cable.😑
I do have a guy in mind I'm yet to ask but had wanted him to do some head work for me on some 799s, kind of makes sense to just freight him the heads, intake and throttle body together when I can afford to. He doesn't flash around big cfm flow sheets but he has a long time in the game and I see the engines he builds seem to dominate in improved production car racing here so he has my confidence. 😁
Bet the shipping coat would start getting ugly indeed. Sounds like you have a qualified shop to work with. Flow numbers are a start but they definitely aren't the whole ball game when it come to an excellent cylinder head. If his stuff wins racing that an excellent sign in my book that should be a good shop. Wish you the best with your project.
Norris Motorsports just wrapped installing the 90mm LS6 intake used in the flow tests above plus a set of Speed Engineering 1 7/8 headers & kooks Y pipe and other basic bolt on's in my 02 Z28. Gained 45 whp peak to peak and 50whp on the top end Very happy with the outcome.
Since this is one of the most comprehensive threads about intakes, I'll post in here
Car is a 03 Z06. Stock heads, BTR Stage2 cam, 1 7/8" LT's and full exhaust, LS3 air bridge and card MAF on SD tune, MAMO ported LS2 TB and Dorman LS2 intake.
Before putting it on, I smoothed out the ridges on the runner sides but did not "port match" (widen the runner to match the heads) or blend the runner ceiling right before the injector (there is a "step" in the runner there). Would you guys find it worth while to "port match" the runner and either grind down the ceiling step/fill it with JB weld to smooth it out? Until I take the manifold off and actually measure the dimensions of my heads and compare them to the intake ports, initial reported differences are that the manifold ports are 0.15"(3.81mm) smaller in width than the head. Keep in mind a normal sized paperclip is roughly 1mm thick. So there is ~2mm worth of material to remove per side of each runner to open it up.
Sometimes it's good to have the manifold passage a bit smaller than the head port to create a bit of an anti-reversion step at the joint. I remember reading about this WAAAY back when SBC's ran the show...
Sometimes it's good to have the manifold passage a bit smaller than the head port to create a bit of an anti-reversion step at the joint. I remember reading about this WAAAY back when SBC's ran the show...
I wonder if that's the idea behind the wedges at the head on the Dorman intake that everyone wants to smooth down.
I wonder if that's the idea behind the wedges at the head on the Dorman intake that everyone wants to smooth down.
Good question! I remember guys using heads ported a bit bigger than the manifold port, the thinking being the airflow goes into the intake port without scrubbing along the intake port walls initially. This was a long while back, but it sounds plausible to me.
12-22-2019 | 11:26 AM
