should throttle body size match opening on intake manifold?
#11
Racetracks
Join Date: Nov 2002
Location: How long is a piece of string?
Posts: 15,668
Likes: 0
Received 0 Likes
on
0 Posts
Re: should throttle body size match opening on intake manifold?
Wow. I wonder what happens with the far cylinders at high flow. That's the intake equivalent of a log-style exhaust manifold, sort of... I've actually seen very similar setups to that, but inverted so the shoebox is on the top. The 350Z intake manifolds are roughly similar to that also I think.
Cool oil pan, is that a factory piece?
If you have time/money/ambition/underhood space, you should make a more traditional manifold setup and use a modern MAF or MAP. The valve covers look like they would set the hood clearance height, and you could probably stuff some long intake runners in the valley. Those intake ports make me drool by the way, it's really cool that they're perfectly circular. So easy to make runners...
I've left the realm of working with what you already have, and have now entered the land of "let's make a badass race setup".
Cool oil pan, is that a factory piece?
If you have time/money/ambition/underhood space, you should make a more traditional manifold setup and use a modern MAF or MAP. The valve covers look like they would set the hood clearance height, and you could probably stuff some long intake runners in the valley. Those intake ports make me drool by the way, it's really cool that they're perfectly circular. So easy to make runners...
I've left the realm of working with what you already have, and have now entered the land of "let's make a badass race setup".
#12
ATGATT
Thread Starter
Join Date: Nov 2008
Location: Wangan
Posts: 10,477
Likes: 0
Received 0 Likes
on
0 Posts
Re: should throttle body size match opening on intake manifold?
The bigger throttle body would only be for greater flow.
If you want to polish something, polish the inside of the 8 outlet ports on the shoebox. If it's a multi-piece shoebox, you could internally polish the whole thing, but the gains will depend on what the surface finish already is, etc..
Arguably the best possible thing you could probably do is to make the shoebox deeper, so there is more space between the 8 outlets and the floor of the shoebox. Then you lose a little velocity (because of the greater volume) but gain a straighter flow path into the 8 outlets. Those outlets, and the runners they attach to, are really what sets most of the velocity into the head. The shoebox should affect the velocity a little, but mostly it's the geometry of the damn thing that will have the most effect on how well it works. It's the same reason that you see velocity stacks on race engines. A plenum box will be around them, but the best thing a plenum box can do is to not interfere with the velocity stacks. There are the obvious tradeoffs with plenum volume and throttle response too, but poor geometry is one of the worst things you can possibly have, because then you can't make the best of the other parts you're working with.
I'm starting to ramble, sorry.
Remember though, the biggest flow restriction is always a throttle plate that isn't open all the way.
If you want to polish something, polish the inside of the 8 outlet ports on the shoebox. If it's a multi-piece shoebox, you could internally polish the whole thing, but the gains will depend on what the surface finish already is, etc..
Arguably the best possible thing you could probably do is to make the shoebox deeper, so there is more space between the 8 outlets and the floor of the shoebox. Then you lose a little velocity (because of the greater volume) but gain a straighter flow path into the 8 outlets. Those outlets, and the runners they attach to, are really what sets most of the velocity into the head. The shoebox should affect the velocity a little, but mostly it's the geometry of the damn thing that will have the most effect on how well it works. It's the same reason that you see velocity stacks on race engines. A plenum box will be around them, but the best thing a plenum box can do is to not interfere with the velocity stacks. There are the obvious tradeoffs with plenum volume and throttle response too, but poor geometry is one of the worst things you can possibly have, because then you can't make the best of the other parts you're working with.
I'm starting to ramble, sorry.
Remember though, the biggest flow restriction is always a throttle plate that isn't open all the way.
This will give you an idea of the level of finish
And yeah, I didn't make a mistake so simple as a throttle that isn't opening all the way
#13
ATGATT
Thread Starter
Join Date: Nov 2008
Location: Wangan
Posts: 10,477
Likes: 0
Received 0 Likes
on
0 Posts
Re: should throttle body size match opening on intake manifold?
Wow. I wonder what happens with the far cylinders at high flow. That's the intake equivalent of a log-style exhaust manifold, sort of...
Cool oil pan, is that a factory piece?
If you have time/money/ambition/underhood space, you should make a more traditional manifold setup and use a modern MAF or MAP. The valve covers look like they would set the hood clearance height, and you could probably stuff some long intake runners in the valley. Those intake ports make me drool by the way, it's really cool that they're perfectly circular. So easy to make runners...
I've left the realm of working with what you already have, and have now entered the land of "let's make a badass race setup".
Cool oil pan, is that a factory piece?
If you have time/money/ambition/underhood space, you should make a more traditional manifold setup and use a modern MAF or MAP. The valve covers look like they would set the hood clearance height, and you could probably stuff some long intake runners in the valley. Those intake ports make me drool by the way, it's really cool that they're perfectly circular. So easy to make runners...
I've left the realm of working with what you already have, and have now entered the land of "let's make a badass race setup".
As far as getting someone to make me custom stuff....nobody is interested in making custom stuff for an engine they have never seen before nor will see again. The few custom stuff I have gotten has required time, begging, and lots of money.
The air filter housing is actually what sets the hood clearance height, and as you can see it sits a good bit higher than the valve covers (well, actually the false firewall sets it...)
(there have been changes made since then, like a third air intake line and reflect-a-gold all over the air intake housing.
Last edited by marlinspike; 04-29-2010 at 10:53 PM.
#14
Racetracks
Join Date: Nov 2002
Location: How long is a piece of string?
Posts: 15,668
Likes: 0
Received 0 Likes
on
0 Posts
Re: should throttle body size match opening on intake manifold?
No, I was saying that the throttle plate is obviously always restricting flow, unless you're at wide open throttle. That's how it works.
Yeah, it definitely can't hurt to clean up around those outlet ports. If that's a one piece casting, that's going to be pretty hard to access much else though.
Yeah, it definitely can't hurt to clean up around those outlet ports. If that's a one piece casting, that's going to be pretty hard to access much else though.
#15
ATGATT
Thread Starter
Join Date: Nov 2008
Location: Wangan
Posts: 10,477
Likes: 0
Received 0 Likes
on
0 Posts
Re: should throttle body size match opening on intake manifold?
#16
ATGATT
Thread Starter
Join Date: Nov 2008
Location: Wangan
Posts: 10,477
Likes: 0
Received 0 Likes
on
0 Posts
Re: should throttle body size match opening on intake manifold?
Oh, btw, there is a guy in Estonia making a corvette-like manifold for these, but I really don't feel like dealing with megasquirt and that's what his setup requires. I'm able to get a perfect AFR map (when the digital component I bought for my mechanical injection works, right now I'm on the back-up full mechanical set up and it gets a decent curve but not perfect).
#17
Racetracks
Join Date: Nov 2002
Location: How long is a piece of string?
Posts: 15,668
Likes: 0
Received 0 Likes
on
0 Posts
Re: should throttle body size match opening on intake manifold?
Yep, that's a factory oil pan. 8.5qts at an oil/filter change baby.
As far as getting someone to make me custom stuff....nobody is interested in making custom stuff for an engine they have never seen before nor will see again. The few custom stuff I have gotten has required time, begging, and lots of money.
The air filter housing is actually what sets the hood clearance height, and as you can see it sits a good bit higher than the valve covers
(there have been changes made since then, like a third air intake line and reflect-a-gold all over the air intake housing.
As far as getting someone to make me custom stuff....nobody is interested in making custom stuff for an engine they have never seen before nor will see again. The few custom stuff I have gotten has required time, begging, and lots of money.
The air filter housing is actually what sets the hood clearance height, and as you can see it sits a good bit higher than the valve covers
(there have been changes made since then, like a third air intake line and reflect-a-gold all over the air intake housing.
#18
ATGATT
Thread Starter
Join Date: Nov 2008
Location: Wangan
Posts: 10,477
Likes: 0
Received 0 Likes
on
0 Posts
Re: should throttle body size match opening on intake manifold?
Depends if they actually want to make money or not. Plenty of race fab shops would make you a manifold in a second. It really isn't any different than any other V8, the flanges and things are the only difference. An engine is an engine, so whether someone wants to make parts only depends on whether they want to make a production run of the same part. A one-off is the same no matter what though.
#19
Racetracks
Join Date: Nov 2002
Location: How long is a piece of string?
Posts: 15,668
Likes: 0
Received 0 Likes
on
0 Posts
Re: should throttle body size match opening on intake manifold?
Oh, btw, there is a guy in Estonia making a corvette-like manifold for these, but I really don't feel like dealing with megasquirt and that's what his setup requires. I'm able to get a perfect AFR map (when the digital component I bought for my mechanical injection works, right now I'm on the back-up full mechanical set up and it gets a decent curve but not perfect).
Last edited by Fabrik8; 04-29-2010 at 10:57 PM.
#20
ATGATT
Thread Starter
Join Date: Nov 2008
Location: Wangan
Posts: 10,477
Likes: 0
Received 0 Likes
on
0 Posts
Re: should throttle body size match opening on intake manifold?
Also, I like that right now my car relies on pretty much 0 electronics, other than the ignition box which does little more than act as a trigger, and that aforementioned digital controller I have for my factory fuel injection, which only takes about 5 minutes to swap out for the mechanical setup when it goes down.
Last edited by marlinspike; 04-29-2010 at 11:00 PM.