Project: 97 6-speed, SC400 supercharged 4.7L V8

scotturnot

Member
Looks the business Scott!

Out of curiousity, what did the discharge port look like on that Whipple? Is it about 4" x 6", and sitting just above the inlets to 1/2/3/4?

Thanks for that pic of the cam lobes; I thought you'd only chamfered the uppermost portion, but wanted to confirm it. You'd think with as many UZ cams that Kelford has probably built, this problem would have been engineered out a long time ago.
Remember my base circles are slightly larger than stock which could contribute to the lobe interferance.

Discharge port is even worse than that, its about 3"x6" clear at the front. Here are some pictures of the intercooler with the plate installed at a slight angle in hopes to redirect it to the center. My hope is the intercooler will act as a diffuser. We shall see.



 

cribbj

"Supra" Moderator
Staff member
Forgot to mention to you, my lobes are hitting the lifter guides too.....

I think your Whipple's discharge port placement may be worse than Zuffen's and my OA's. Wonder what they (Whipple) do with a domestic application? Probably have a lot more room from front to rear with a domestic motor, so they just put a longer snout on it and move it back so it's centered. Still, I would think that would only move the problem to the middle cylinders.

It would be interesting to see the inside of a Whipple manifold, to see what they're doing to divert the air flow.
 

scotturnot

Member
Forgot to mention to you, my lobes are hitting the lifter guides too.....

I think your Whipple's discharge port placement may be worse than Zuffen's and my OA's. Wonder what they (Whipple) do with a domestic application? Probably have a lot more room from front to rear with a domestic motor, so they just put a longer snout on it and move it back so it's centered. Still, I would think that would only move the problem to the middle cylinders.

It would be interesting to see the inside of a Whipple manifold, to see what they're doing to divert the air flow.

So yours hit too? I wonder if this a common happening with performance cams in the 1uz? I would have actually rather took a die grinder to the heads but was too far in the build to pull the heads. The cam also hit one spot on the exhaust cam where there is a factory clearance, I very carfully removed some meat on the head there. I still dont have a lot of clearance but do figure I need much.

Regarding the whipple exit, I agree with you, it may be worse, I hope I have at least improved it.
 

cribbj

"Supra" Moderator
Staff member
BTW, what are you doing for an IACV?

You're using an Infiniti TB aren't you? There's not an IACV on it, is there?
 

scotturnot

Member
BTW, what are you doing for an IACV?

You're using an Infiniti TB aren't you? There's not an IACV on it, is there?

John, Yes I was intending on using the Infiniti TB. I have to be honest here, I have not even explored this. In fact I am not even sure it is required. Is it part of my stock TB? Please let me know everything you can about it, maybe you will save me some time. Did you have one on the engine you dynoed?
 

scotturnot

Member
Its funny you bring this up, I was studying the TB and have several questions about it. Can it be ran in any position? i.e. upside down. There are two small Holes by the butterfly, These are meant to be on the bottom, they are fed by what looks like Vacum lines. Other than that it seems I could flip it over.
 

cribbj

"Supra" Moderator
Staff member
The IACV is just a small valve that lets in small quantities of inlet air and controls idle speed. On the stock Lexus setup, it's mounted on the front of the manifold. On the Richwood setup, normally Andrew machines that inlet elbow to take the Lexus IACV. I didn't see this machining on your elbow which is why I asked.

The GM TB's incorporate a stepper type IACV (same as Lexus) into the TB, which makes for a cleaner setup IMO. It's certainly cheaper, as the GM IACV costs about 25% of what the Lexus one does. On the last two dyno sessions I ran a GM TB with the integral IACV, and it worked fine.

Some guys run their modified engines without an IACV, and just set the idle with the main butterfly, like we did in the old days with carbs, however what you don't get with this, is automatic idle control when the A/C kicks on/off, nor when you put a big load on the power steering pump, or the alternator. Nor do you get an automatic high idle for fast warmup after a cold start.
 

scotturnot

Member
The IACV is just a small valve that lets in small quantities of inlet air and controls idle speed. On the stock Lexus setup, it's mounted on the front of the manifold. On the Richwood setup, normally Andrew machines that inlet elbow to take the Lexus IACV. I didn't see this machining on your elbow which is why I asked.

The GM TB's incorporate a stepper type IACV (same as Lexus) into the TB, which makes for a cleaner setup IMO. It's certainly cheaper, as the GM IACV costs about 25% of what the Lexus one does. On the last two dyno sessions I ran a GM TB with the integral IACV, and it worked fine.

Some guys run their modified engines without an IACV, and just set the idle with the main butterfly, like we did in the old days with carbs, however what you don't get with this, is automatic idle control when the A/C kicks on/off, nor when you put a big load on the power steering pump, or the alternator. Nor do you get an automatic high idle for fast warmup after a cold start.
OK, so its the junk on the front of the stock intake. I did get away without it on my last engine in the fashion you just described but Mitch was recomending I run one. Guess I have more stuff to figure out.
 

cribbj

"Supra" Moderator
Staff member
I'd suggest you run one, particularly if you're going to have Mitch come out and tune your AEM. It's one of the few aftermarket EMS's that can control a stepper type IACV, and map it separately.

It would be a shame to have one of the few EMS's that is capable of it, and one of the few tuners who really knows that EMS, and not have an IACV on the motor.

As I see it you probably have a few choices:

1) You can pull off your intake elbow and have it machined to take either the Lexus or someone else's IACV (there are kits and adapters out there on the Internet for people who want to add an IACV to a setup that isn't already equipped.) If you do this, then you'll have to add a line from in front of the TB back to the IACV, or just put a little K&N air filter on it (that's what I have on my Supra setup currently.)

2) You can change your Infiniti TB and go with a GM that already has the IACV integrated in it. No new lines to run this way.

Here's a post from my thread where I was describing the GM TB and its advantages: http://www.lextreme.com/forums/showpost.php?p=77845&postcount=97

In this post: http://www.lextreme.com/forums/showpost.php?p=78024&postcount=104 you can see the machining that Andrew does on the intake ell for the Lexus IACV (all the way to the right of the ell photo). I have it blocked off with a piece of ally plate.

Here: http://www.lextreme.com/forums/showthread.php?t=7904&page=15, and starting in post 129, is where I modified the GM TB to allow the integral IACV to work. Not sure why this was necessary, but perhaps this particular TB originally had a different IACV arrangement. Anyway, the mod worked and so did the IACV
 

scotturnot

Member
Well John you really got me thinking about my TB choice. I now have bought two different GM TB's to look at as well as my Nissan. Between them all I am sure I will find the magic combo. The more I thought this all out the more I like the IACV built in the TB. Thanks for all your help on this John.

Next up, I got back to the cams and valves today. First I got to say, it is a bit of a trick getting a Dial indicator on the lifters but after some time I finally was able to do it. I first set the degrees on the intake cams, once I got them set I checked Valve to piston clearance. I was pleased to find the minimum during the rotation cycle is .100"! Kelford says .080" minimum so I can now breathe a sigh of relief. I didn’t get time today to check the exhaust in relation to the intake but I hope to find good news there as well.
 

scotturnot

Member
Well, I am trying to decide what to do about throttle body selection. Right now I have three choices
Choice #1 is the stock. Stocker is 70mm dia. I dont think this is even a option.

Choice #2 is the Nissan Q45 TB. This unit is 80mm dia. This was my original plan until I realized the GM units had a IACV on them.

Choice #3 is the GM TB. This unit is a 75mm. I have 2 of these, one is stock and I was considering machining it out to around 78mm like John Cribb's is. Is the trouble worth 3mm? The other unit I have is modified. It has the following mods.
Ported and polished throat / interior.
Polished return spring
Shaved / sanded & polished exterior.
Throttle blade is thinned and polished.
Blade screws are cut and reinstalled with thread-lock.
Bump stop modified to ensure fully opened operation.
Shaft cut / halved to reduce air restriction.
IACV and TPS sensors.
IACV polished.
IACV/TPS screws polished.

Here are some pictures
Left to right Stock/GM/Nissan



Now here is a look in the throat of the GM

Side of the GM, it sure is nice and short.

Now a look through it with the butterfly open. Notice the cut shaft, I think removing half the shaft to open it up and help air flow has some nice merit to it. Also the flush screws help and of course the ported polished bore helps. The only thing stopping me on this TB is its 75mm bore.

Nissan opened, Note shaft still there.

Stocker opened


So, What do You guys think? is 75mm going to feed my engine enough?
 

JBrady

Moderator
Scott,

Hate to say it but polishing the TB will almost certainly reduce its capacity.

The smooth sides actually increase the boundary layer reducing flow.

Shame after all the pretty work but you should bead blast that thing.
 

cribbj

"Supra" Moderator
Staff member
Scott, if I were you, I'd talk to Mitch & go with his recommendation.

He can tell pretty well from his tuning parameters at what point the TB is becoming a bottleneck for the engine.
 

scotturnot

Member
Scott,

Hate to say it but polishing the TB will almost certainly reduce its capacity.

The smooth sides actually increase the boundary layer reducing flow.

Shame after all the pretty work but you should bead blast that thing.
I am shocked to hear this, Makes me wonder why everyone used to port and polish intakes and heads. We used to do it as common practice on our racing two strokes. Please explain more how it increases the boundry layer. Thanks for the heads up.

Scott, if I were you, I'd talk to Mitch & go with his recommendation.

He can tell pretty well from his tuning parameters at what point the TB is becoming a bottleneck for the engine.
Sent him a email, awaiting his response.

What's wrong with stock? certainly not a flow restriction?
I would stay stock. Makes things easier and TB is not the bottleneck of the whole system.
Well if you guys dont feel the stock is a flow restriction the the 75mm GM should be great! It makes me feel better knowing the stocker performs plenty good. I really need a IACV and the GM makes that easy and clean, cant get that from the stocker.
 

JBrady

Moderator
I am shocked to hear this, Makes me wonder why everyone used to port and polish intakes and heads. We used to do it as common practice on our racing two strokes. Please explain more how it increases the boundry layer. Thanks for the heads up.
As the theory goes by breaking the surface into small irregular objects (rough surface) the "cling" that air wants to do is also broken into smaller pieces and small turbulent areas end up acting like air "bearings" hence reducing the boundary layer. The smooth surface of a polished port allows the air to have a smooth continuous "grip" that builds up and effectively reduces air flow as the boundary layer (dead flow) grows and reduces the effective port size.

Polishing the port looks pretty but does nothing to create power.


Well if you guys dont feel the stock is a flow restriction the the 75mm GM should be great! It makes me feel better knowing the stocker performs plenty good. I really need a IACV and the GM makes that easy and clean, cant get that from the stocker.
Actually, I have to disagree with the others advice. If this were a blow through like a turbo I would say the stock TB is definitely large enough. But, since this is a draw through application a larger TB can help with response, compression efficiency and peak power. Again, you get into trade offs and running an IACV is highly advisable... so, IMO run the GM TB or the Q45 and create an idle air port.
 

JBrady

Moderator


Gotta say this doesn't look right. I think it will effectively reduce your intercooler flow surface reducing efficiency. The basic idea is good I would
just lower the deflector by about 3/4" creating a mini reverse scoop instead of the pictured blocking plate. This would allow that part of the core to flow and still deflect/help balance the charge.
 

Attachments

JBrady

Moderator
Actually, after reviewing your previous pics it looks like that core will be fairly close to the floor of the intake. It probably will not need any additional deflection. JMHO.

I am somewhat concerned that you have solid welded aluminum core and water connections. Some flex could prevent cracking. Cracked water passages in the intake could be very bad. It is of course very easy for me to criticize and I don't want to come off as just pointing out flaws. Your effort is huge and impressive. Just trying to point out pontential problems. Much easier to fix now than later on many levels.
 

scotturnot

Member
As the theory goes by breaking the surface into small irregular objects (rough surface) the "cling" that air wants to do is also broken into smaller pieces and small turbulent areas end up acting like air "bearings" hence reducing the boundary layer. The smooth surface of a polished port allows the air to have a smooth continuous "grip" that builds up and effectively reduces air flow as the boundary layer (dead flow) reduces the effective port size.

Polishing the port looks pretty but does nothing to create power.


Actually, I have to disagree with the others advice. If this were a blow through like a turbo I would say the stock TB is definitely large enough. But, since this is a draw through application a larger TB can help with response, compression efficiency and peak power. Again, you get into trade offs and running an IACV is highly advisable... so, IMO run the GM TB or the Q45 and create an idle air port.

OK, I see what the thought process is behind the polish, Cant think I would see anty difference between polished and not. The porting I think is worth the work that was done. Its funny you bring up the argument that a blow thru TB verses a draw thru makes a difference. I have actually told this to 3 other members and told them thats why I was worried the TB might be to small. Right now I am either using the GM or adding a IACV to use the Q45. There is a point where the TB can become to big, I just dont want to reach that point.
 
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