Modify my HO mani or start from scratch? - Boost Forum
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So, I'm going to be running a 75mm LS1 TB on my LD9 and was planning on running the HO manifold. Well we know the TB opening on the manifold is only about 60mm or a little larger. Theres just no way to get the larger TB onto the manifold. So, what I did was buy 3x5" rectangular tubing planning on cutting the HO plenum off leaving the runners and weld the HO runners onto the new plenum, which I'd match closely in volume to the original HO but with a larger opening in the front for the larger TB. My question is this: Would I see a better benefit to just make a complete custom intake with the new plenum and make straight runners or will the HO runners provide enough flow to not really matter. I'm looking for a more daily driven car rather than a strip only. So I'm leaning towards my original idea, but just what to know what people think about the HO manifold on boosted apps as far as flow. Also, running a 086 head aswell.
"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous
get a flange, a(Mig for alum.) welder, and a sawzall.
Chris
'02 Z-24 Supercharged
13.7 @102.45 MPH Third Place, 2007 GMSC Bash SOLD AS OF 01MAR08
All my alum. I TIG....no MIG for me. I guess your voting for building one from scratch eh.
"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous
Good results were achieved with the Ho manifold but if you like building stuff, do a new manifold. I personnaly would run an Ho manifold and be done with it. BUT, you have the skill to make one. I don't see the justification in spending money for something that will most likely not change much since it will be on a DD.
Gilles
2.3 Ho
I'm in the same predicament with my turbo hybrid 2.3/2.4 with a 75mm LS1 tb, what I'm going to do is buy an LS1 tb spacer and have it tigged to my HO intake then match the opening inside to promote smooth flow. Finally I'm going to have it extrude honed.
Yeah, I thought about that but either way your gonna have to cut open the manifold to smooth things out on the port side of things. I just spent like $35.00 for 3"x5"x30" 0.250 wall 6061 tubing since that is close to what the HO plenum is already....but since I'm already half way to a new manifold, wondering what others would do. I like the look of the HO but if I'm gonna go through all the work of taking the runners off and hack apart this tubing for no real advantage........=no
I've already made the LS1 TB adapter, but a spacer woulda been simpler....lol...didn't even think about it.
EDIT: Doesn anybody know where to get some round tubing to oval port adapters?, kinda like these:
Otherwise I'll have to make them...booooooo, but I'll do it if I have too.
Edited 1 time(s). Last edited Saturday, March 07, 2009 7:33 PM
"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous
Quote:
All my alum. I TIG....no MIG for me. I guess your voting for building one from scratch eh.
No, Just after the OE flange, where the "pot" is at the widest.... a LS1 Flange , (get copy paper all the newbeys, not you Josh.) you can find one in a junk yard on a North star V8 from a 98 car up, all you do then is cut the bottom off of it, where the water goes through on the north star,
This is entirely Function Over Form, it works and is cheep.
Now if you like Form Over Function, fab it up.
As soon as mine is done, I will send you a pic.
Chris
'02 Z-24 Supercharged
13.7 @102.45 MPH Third Place, 2007 GMSC Bash SOLD AS OF 01MAR08
Personally I'd put a new plenum on with the right flange... no need to really mess with the runner length unless you're gonna tune the runner length on a dyno...
-Chris-
-Sweetness-
-Turbocharged-
Slowly but surely may some day win this race...
Bpow wrote:check out this site....they might have something that will work.
http://www.rossmachineracing.com/intakepartspage.html
Looking at there oval-runner tubing it looks promising, the width would only require 0.120" porting on the head(0.060" on each side) but the height would require 0.125" on each side, top and bottom, of porting to match...thats a little much I think, but I have yet to port an 086 so I really dont know. Maybe possible or close at least.
Taetsch Z-24 wrote:No, Just after the OE flange, where the "pot" is at the widest.... a LS1 Flange , (get copy paper all the newbeys, not you Josh.) you can find one in a junk yard on a North star V8 from a 98 car up, all you do then is cut the bottom off of it, where the water goes through on the north star,
This is entirely Function Over Form, it works and is cheep.
Now if you like Form Over Function, fab it up.
As soon as mine is done, I will send you a pic.
Chris
I'd be interested in a pic....that would be badass.
SweetnessGT wrote:Personally I'd put a new plenum on with the right flange... no need to really mess with the runner length unless you're gonna tune the runner length on a dyno...
-Chris-
Well, I look at it this way....there is no real dyno proof of the HO intake really under a boosted environment anyway. Many people are running it with boost yes, but many builds are very different in several different ways. No real way to narrow down gains/losses caused by running the HO mani in boosted applications anyway, so....at what point to you just say F'it and admit that there is no proof one way or the other. Basically, I or you have no proof of performance with the overdone HO mani with dyno proof so what do you do when you have no evidence to back something up in either direction? My answer is do whatever the hell you want since there will still be no proof....not saying build a hack job, but rather build something that is rather familiar to other designs for similar sized engines in the aftermarket. I dont know......it's the only thing that makes since to me. Right now I'm going to pick up some 3"x0.250"wall tubing and cut the long side of my 3" x 5" rectangular tubing and weld on the round tubing onto the backside to match closer to most aftermarket intakes and then find some runner material like Bpow found and go from there. Maybe I'm off on the wrong side of the street but I'm going to do something. I'll probably wait to see what you got there first Chris, all I got right now is a 3x5 .250wall rec. tubing and a 75mm TB which wont fit on the HO...so.........
^Don't take this the wrong way there Chris(Sweetness), just talking out loud with what I've seen around here and what I got to work with. I know the HO is probably a decent design....but more directed towards what it was designed for....a 2.3L NA with .410 cams w/ a sweet-spot @ ~6200RPM.....doesn't really mean it would be good with 20lbs of boost. Then there's the argument of "the best boosted car WAS the best NA car"....idk.
"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous
Joshua, I agree fully.. the H.O isn't a tested and proven runner length / plenum design for anything other than the quad 4 N/A... maybe it's a choke point? Who knows.
All I'm saying is if you're gonna go custom, and go through all that work to go with an LS1 and design and fab up a manifold... you should go the extra mile and tune the runner length properly. It's a super annoying and possibly expensive procedure but I don't see the point in just putting together a manifold with "any" runner length when you're going to that level to customize something for your purposes to run that nice big TB.
I'm pretty happy sticking with a H.O since I've got zero welding skill and a thin pocketbook to have something truly nice fabbed up... but that's out of sheer complacency. Curiosity stirs me to try for something better but as always with this hobby, the wallet dictates the direction I go in. 
No matter what keep us updated with pics and all the good stuff!
-Chris-
-Sweetness-
-Turbocharged-
Slowly but surely may some day win this race...
I see your point, but honestly if I do make a manifold, I can guarantee I wont have the ability to dyno tune it since I live 200miles away from the closest dyno and I can't exactly bring tools and welder with me to the dyno shop. So.....I still don't know what I'm gonna do. I have a feeling I'm gonna make a nice looking manifold, but afraid it's gonna suck. I just I will hope for the best, anybody got any good info/resources on design considerations?
"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous
Well if my memory servers me correctly when the Quad4 HO first came out Jim Feuling built a turboed 750 hp one and I believe it was running a stock HO intake. So I feel comfortable with a modded HO intake, although the custom sheet metal ones look so friggin cool.
Function
________________________________
Form
Chris
'02 Z-24 Supercharged
13.7 @102.45 MPH Third Place, 2007 GMSC Bash SOLD AS OF 01MAR08
There really seems to be an entire LACK of any design considerations for boost intake manifolds, humbolts resonance is really the only method to tune pulses but that has very limited effectiveness under boost. That and it is only good for like a 300rpm range wherever I decide to put it in the power band. It seems the only way is dyno data to narrow down the designs. I already knew that but I was hoping I'd find something.....but no......
"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous
I would really love to see pics of a modded HO intake mani with a plate welded on for a huge LS1 tb
~2014 New Z under the knife, same heart different body~
______________________
WHITECAVY no more
2012 numbers - 4SPD
AUTOMATIC!!
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^I already got the plate and everything, but it is kinda ugly honestly. Unless I spend COUNTLESS hours smoothing the manifold and then try to somewhat better match the square entrance on it (due to the TB flange). Damn, It'd be easier to box in the manifold. Then I'm back to my original idea of using the 3x5" rec. tubing and weld the runners onto the top, but then to me that looks like the most restrictive part of the manifold. Does anybody have flowbench data on the HO? -Damn, that will probably be no good since the biggest restriction would be the ~64mm TB port....F'ers.
It's all possible, but damn, I'm looking for somewhat easy now a days. By the term "easy" I'm still including fabbing up a whole new manifold because really, that would be easier than F'n with the HO trying to make it look good. The width of the whole damn thing isn't much bigger than the TB, I really think this TB is way overkill for this manifold and the overall throttle response and respiration will suffer. Who knows.......I really do wish somebody does know, cause I sure as hell will admit I don't know jack @!#$ for boosted apps and what I do know only applies to N/A engines. This whole searching for info gives me entire lack of trust with most aftermarket intake designs, cause you know alot of company's will put form over function just to sell their 'pretty looking' intakes. Then what does that leave me, not a damn thing, cause all I can hope to do is make a manifold "similar" in design to whats available. It's time to find designs with dyno results, then use those designs as the models to witch I try to follow, but there's not many of those out there. At least not for 4cyl guys.
"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous
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