General intake questions

[Jim Reym]

I’m wondering about a few things that I’d need to address if I go with engine and I realize this might be the wrong crowd but clearly you folks have lived with these motors so you’ll have lots of experiences to draw on.

My build starts with a clean sheet of paper so there’s lots of possibilities. Right of the mark I see the stock intake is not going to work so I’m thinking ITB using 2 pairs of 4- 41 mm GSXR750 TBs married to the stock elbows cut to make vertical stacks. ITB gives great control over air charge so the secondaries can go away. It’s possible go even further but then it starts getting the injectors involved and without a flow bench that’s not where I’d venture to go.

On the LS I changed the intake to LS6 and it woke the engine up so intakes are huge in the power making department. But as I wrote the stock one won’t do and 8 polished stacks will look killer atop the engine.

I see a lot written about carbon build up on the intake valves and for sure a lot of that is due to the stupid EGR setup. The LS1 had EGR and those engines too have the same carbon issues and in 02 the engineers found another way, essentially by tuning but also by adding a separator box which I notice the 3.4 has also so I’m thinking delete EGR all together EDIT I got EGR and PCV mixed in together. Clearly the separator box is PCV and nothing to do with EGR. I think carbonizing of the intakes though has a lot to do with reversion of exhaust gas in the valve overlap and I read the Cam on the 3.4 is 3/4 race so the exhaust valve is open a lot longer than what’s typical in a mild crammed engine and without a good scavenge a good amount of hot gas is going to finds its way back up the intake. Thats maybe why the crap is backed all over the secondary butterflies. So what I’d do is build properly matched headers and flow them through high flow 200 cell Cats and dump the exhaust with the least restriction, probably a couple of Vibrant ultra quiet resonators and that’s it. This method should pull the intake charge into the combustion chamber and avoid reversion and with a bit of luck make the engine scream.
What do you think?

 

[luigisho]

If you can get those independent throttle bodies to go I'd love to see them. Sounds good to me. If you can eliminate egr that sounds great. There have been a few over the years to do that on a stock car but I don't see them around in a long time. Not sure what requirements are up there about running that car and emissions and all that.

 

[Jim Reym]

If you can get those independent throttle bodies to go I'd love to see them. Sounds good to me. If you can eliminate egr that sounds great. There have been a few over the years to do that on a stock car but I don't see them around in a long time. Not sure what requirements are up there about running that car and emissions and all that.

Emissions testing was cancelled this year, so the only issue is passing the visual when I get the car certified upon registering it and that’s done by a licensed mechanic so I don’t believe it’s much an issue. And it’ll still be one of the cleanest engines on the road.

 

[Jim Reym]

I thought that going ITB could do away with the secondaries altogether but after reading why the big Bikes have something similar I believe it’s more important than ever to have functioning secondaries. It has to do with pulses, vacuum, mass and velocity. Each cylinder wants to be filled every 2 nd revolution and that’s going to created a pulse of high and low pressure, with engine revs giving the frequency. Now the injector is just spraying under the smaller primary port and at lower engine speed the pulse is going to be long and hence the velocity of the air mass is much smaller than when the piston is moving fast at high revs. So if the large port is open all the time it’s likely the air fuel ratio is going to affected at lower revs because a lot of the fuel spray wont get picked up by the majority of the airflow which is now going through the big secondaries.
The issue is mitigated when there’s a single manifold feeding all the cylinders because of the mass velocity of air created by all of the cylinders working in sequence, but with ITB, especially at lower revs the air flow to each cylinder is almost off and on and velocity almost non existent and that will make for difficult throttle management. So information on the control of the secondaries is scant but as I understand it the butterfly’s open around 3k, but how does that happen? Is there a step motor that incrementally opens them a fraction beginning at (x) rpm and repeats it at another rpm until they are fully open at (y) rpm? What happens when TPS shows closed throttle?

 

[luigisho]

There is a module that mechanically opens the secondaries around 3400rpm via a cable and pulley (sort of like old school throttle cable before drive by wire setups). There have been failures of this module reported by several owners. Some replaced the IMRC (intake manifold runner control) and others just wired the secondaries to be open at all times. I don't remember if it is open vs closed or graduated opening of the secondaries. I am inclined to think it is more likely just open vs closed but I am not strongly certain of that.

You can try and search the v8 section of this forum and see what is still archived about this with the search function. You can use the old v8sho website https://www.v8sho.com/SHO/96shohome.html
There is a google search bar on the website to search info posted within the website and a general google search option as well. Helps cut down the search time.

 

[Jim Reym]

Great stuff. I went to the other site and found the IMRC opens and closes the secondaries around 3000, though 3400 was mentioned a couple of times too. It also closes the butterflies at 6800, to avoid over revs. The description of the operation from a member who watched the IMRC open said it happened fast. It’s is all controlled by the PCM. There was also a lot written of the lower butterflies being gummed up and how that likely led to the IMRC failures. IMHO that’s got poorly functioning PCV written all over it. I don’t think EGR would affect it much other than it’s hot air, so perhaps it does. Anyway thanks for the info, it really helps.

 

[luigisho]

Yeah they get gunky from either or both. Catch can couldn't hurt nor egr elimination as you were mentioning. Egr tends to clog where it enters the intake over time so, yeah messy.

 

[Jim Reym]

I wondered how it was that GMs peopled found they didn’t need EGR on the LS engines after 01 and it seems it’s the cam overlap where the exhaust valve is still open after the intake valve is pulling in the fresh charge and some of the exhaust is being pulled back into the combustion chamber too. That in effect replicates what the EGR system does. In any event earlier I said the SHO 3.4 cam was referred to as 3/4 race and though I don’t have the numbers on hand I think it’ll be having major overlap.
Scanning around tonight on EGR I came across this which may give strength to my argument.
‘On my '97 Taurus SHO I have the EGR system disabled. This particular engine is very sensitive to intake manifold and surge tank heating. I found that while cruising on the highway in 90F temps the EGR system would raise the surface temp of the intake track ~40F.

That plus the fact that the head and reverse flow coolant design are superior means no pre-ignition on 87 octane, no EGR and a 10:1 CP.

I do have a custom chip that will take care of the codes so no SES for me because of it.

 

[luigisho]

I totally agree with that. This is all emissions approach by ford engineers. Back when the earlier v6 cars were the huge bulk of owners on this forum, several deleted egr in those cars too. In fact, in early models there were California emissions models that had egr and the rest of the manual cars from 89-91/92 did not have egr. When people did egr delete they closed off the exhaust and intake manifold egr ports and installed non california pcm's (computer) to run it.

 

[Jim Reym]

I’ve been doing quite a bit of reading on ITB sizes, runner length and trumpets lately and have an idea how this is going to look and work. One consideration I don’t have sorted yet, and there’s lots of discussion online, is injectors. The stock injectors spray just under the primary manifold port and the GSX ITB spray just under the butterfly so I mused which location is better. Then it occurred to me why not both? Using the IMRC as the cue activate the second injector to activate at 3000 rpm with a fine mist. I posed this to Mr Google and apparently the Honda 600CBR has a second injector way back at the air box that activates a higher RPMs. So now with both injectors operating and the lower one operating at lower revs can be smaller lbs/min. From what I read having a second mister cools the air charge combustion temperature and reduces detonation potential. And that means the ECU doesn’t retard the spark and the engine makes more power.
What do you think?

 

[luigisho]

You are in mostly uncharted waters with this modification route on this engine. Not alot of v8 swaps with custom intake designs that I can remember. Keep looking around and posting what you find out.

 

[FoolishEarthling]

Love that 33 Stradale! Most beautiful car ever IMO.

 

[stephen newberg]

Na, Porsche 911 wide hip...

pax, smn

 

[Jim Reym]

Ok, making progress on how the ITBs will work, at this point the choices are Kawi Ninja, Suzuki Gsxr, Hayabusa and Honda CBR throttle bodies sitting on top of modified SHO intakes with trumpets on top going to a common air box. The air box is needed to have clean air and a place to dump crankcase fumes. There are two injectors per cylinder, one in the stock location and a second on top of the throttle bodies. An ECU operating in conjunction with the PCM controls when and how much fuel sprays. At this point I know this is physically possible and the mapping has to be done on the running engine so that’s much down the road. The length of the runners, and trumpet size comes down to the demands imposed by the valve (cam) timing and learning duration and lobe separation will help a lot but I can’t find anything online. Length of the runners plays a major role in engine performance and millimeters count so this is going to take a lot of analysis. If you folks know or come across info re cam info on the engine it’d be great to hear from you.

 

[luigisho]

Any of this help?
https://v8sho.com/SHO/FactoryCamPerformanceSpecs.htm

 

[Jim Reym]

That’s great and got me looking at the variables. On the way I stumbled,(stumble is a good way of describing how my knowledge advances on the topic), I found this conversation on the Integra forum where a knowledgeable guy says the way to go is plenum and a single throttle body to get the ram effect. https://www.team-integra.net/threads/intake-cam-lift-vs-itb-runner-length.55050/ It bears a closer look but obviously simplifies things as I need a plenum anyway. He says that a race team achieved better times with a single butterfly than multiple ones due to the Helmhotz effect in the plenum.

 

[gamefanatic]

Depending on how you wire things up the stock ECU won't be able to support the extra injectors. You'd be better off going with an aftermarket ECU if you want to control those separately. Haltech Elite 2500 comes to mind.

 

[luigisho]

Does that leave stock phlenum or fabricate a custom one?