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  #46  
Old 11-19-2005, 07:00 PM
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Quote:
Originally Posted by mbtoloczko
Its probably not quite like that. There is 13% more lift, but the throttle body butterflies are what control the amount of air that gets into the engine when you're just cruising around at part throttle. Its more likely that by changing the duration and the lobe centers, you've slightly decreased the efficiency of the engine at lower rpms, and so mileage is slightly reduced.
Agreed! My guess it that it's also coupling with the Impreza fpr (i.e. rich AFR). Yet another reason to get on that MAF bypass, Chike
-Bill
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  #47  
Old 11-19-2005, 08:10 PM
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Quote:
Originally Posted by SVXRide
Agreed! My guess it that it's also coupling with the Impreza fpr (i.e. rich AFR). Yet another reason to get on that MAF bypass, Chike
-Bill
I would in a New York minute if I could pick up a spare intake tube and airbox. Otherwise, I'd like the Stage 2v5...
Quote:
Originally Posted by mbtoloczko
Its probably not quite like that. There is 13% more lift, but the throttle body butterflies are what control the amount of air that gets into the engine when you're just cruising around at part throttle. Its more likely that by changing the duration and the lobe centers, you've slightly decreased the efficiency of the engine at lower rpms, and so mileage is slightly reduced.
Understood. I'll have to monitor my gas mileage over a couple more tanks to see just how significant of a change there has been. I have been getting on the throttle a lot more of late - I just love taking it into the 3,000+ rpm range! The sound gets higher pitched like a Porsche and the car really takes off...

-Chike
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  #48  
Old 11-19-2005, 08:46 PM
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Quote:
Originally Posted by Chiketkd
I would in a New York minute if I could pick up a spare intake tube and airbox. Otherwise, I'd like the Stage 2v5...

Understood. I'll have to monitor my gas mileage over a couple more tanks to see just how significant of a change there has been. I have been getting on the throttle a lot more of late - I just love taking it into the 3,000+ rpm range! The sound gets higher pitched like a Porsche and the car really takes off...

-Chike

Chike,

1. Why not go ahead and do the bypass mod now and worry about a spare snorkus and airbox later? Honestly, when do you really think Michael is going to have the time to do the OBD-II work?

2. "I just love taking it into the 3,000+ rpm range!" Oh, yeah, is this the same guy who said he's only going to take one run on the 25th?

-Bill
p.s. interesting to note that my ram air kicks in right before your cams kick in
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  #49  
Old 11-19-2005, 09:05 PM
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Quote:
Originally Posted by SVXRide
Chike,

1. Why not go ahead and do the bypass mod now and worry about a spare snorkus and airbox later? Honestly, when do you really think Michael is going to have the time to do the OBD-II work?

2. "I just love taking it into the 3,000+ rpm range!" Oh, yeah, is this the same guy who said he's only going to take one run on the 25th?

-Bill
p.s. interesting to note that my ram air kicks in right before your cams kick in
1. I can't cut up my stock airbox and intake tube at this time. I see LAN 'approaching' the completion of the Stage 3 and he's actively looking for a '97 LSi. One of the buyers of his stage 3 kit owns an OBDII SVX, so he'll need to have this software available around the same time he starts shipping those kits out...

2. I don't romp on it from a standstill. Once the car is moving I like depressing the throttle as I accelerate so that shifts occur around 3,500-4,000rpms (roughly 50% throttle).

Also, I'll keep taking runs on the 25th until they boot me off! (seriously, I'll probably do two at the max unless I'm kicked out after the first)

-Chike
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  #50  
Old 11-19-2005, 09:30 PM
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First SVX with performance camshafts!

Congrats Chike! but jsvxstyle SVX has cams plus alot of headwork. Dayle from motorsport warehouse said "this cars got more performance mods that work correctly then anyone elses Ive seen" I have seen Yon's SVX and I can say without a doubt it's true.
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  #51  
Old 11-19-2005, 09:30 PM
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Quote:
Originally Posted by Chiketkd
1. I can't cut up my stock airbox and intake tube at this time. I see LAN 'approaching' the completion of the Stage 3 and he's actively looking for a '97 LSi. One of the buyers of his stage 3 kit owns an OBDII SVX, so he'll need to have this software available around the same time he starts shipping those kits out...

Okay, let's say 6 to 9 months..

2. I don't romp on it from a standstill. Once the car is moving I like depressing the throttle as I accelerate so that shifts occur around 3,500-4,000rpms (roughly 50% throttle).

depressing the throttle = acceleration

Also, I'll keep taking runs on the 25th until they boot me off! (seriously, I'll probably do two at the max unless I'm kicked out after the first)

Hey, just get under the car and rig up a "diaper" out some absorbent material and canvas (they actually sell them for dedicated drag cars so they don't "mess the track" if the bottom end goes..

-Chike

123456 see comments above
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  #52  
Old 11-19-2005, 09:41 PM
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Quote:
Originally Posted by alltrac
Congrats Chike! but jsvxstyle SVX has cams plus alot of headwork. Dayle from motorsport warehouse said "this cars got more performance mods that work correctly then anyone elses Ive seen" I have seen Yon's SVX and I can say without a doubt it's true.
I'll have to adjust my sig then. I was only aware of Frank Aragona's modified EG33 - when last did jsvxstyle post on this Network? What did he do to get around the MAF issue?

-Chike
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Last edited by Chiketkd; 11-19-2005 at 09:45 PM.
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  #53  
Old 11-19-2005, 09:45 PM
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Quote:
Originally Posted by Chiketkd
I'll have to adjust my sig then. I was only aware of Frank Aragon's modified EG33 - when last did jsvxstyle post on this Network? What did he do to get around the MAF issue?

-Chike

Victor,
I remember seeing posts from jsvxstyle when I first joined the network. I seems like he hasn't posted in over a year. I don't remember him ever posting regarding 1/4 mile times for his car. I seem to remember he had a repair shop that did primarily work on Porches....
-Bill
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  #54  
Old 11-19-2005, 09:57 PM
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Quote:
Originally Posted by SVXRide
Victor,
I remember seeing posts from jsvxstyle when I first joined the network. I seems like he hasn't posted in over a year. I don't remember him ever posting regarding 1/4 mile times for his car. I seem to remember he had a repair shop that did primarily work on Porches....
-Bill
Yet another one of those obscure members who came and left. If he does have an SVX with ported heads (i.e. increased displacement) and performance cams that thing would be a beast - but he would have needed to convert the MAF to a MAP system or use a universal MAF and new engine management software.

During my digging on intake cams specs, I came across these for a variety of Porches on Rennlist...



Needless to say most '90+ Porsches are using well over 10mm of lift on their camshafts with alot of overlap between the intake and exhaust cam durations. I can't imagine the specs a Porsche tuner would have gone with if he went wild on an EG33!

-Chike
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Last edited by Chiketkd; 11-19-2005 at 10:01 PM.
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  #55  
Old 11-20-2005, 01:13 AM
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Quote:
Originally Posted by Chiketkd
One other thing Danny. You quoted me when I was speaking about the 'idle' with the new cams, not the performance (which is very misleading).
I was reading it again, where was my head? all i think of is performance performance... sorry guys i didn't read idle...
as for my upgrade, i will be shipping extra heads where i can do R&D on especially the springs and lifters...
The cams will be done in the states (according to harvey's stage 3)
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  #56  
Old 11-20-2005, 11:57 AM
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Thinking about pressure drop on the intake system. The primary cause of pressure drop at high RPM is the pressure required to accelerate the air to a velocity of approximately 7000 fpm. This velocity is necessitated by the 3” diameter of the MAF and by what appears to be the 2.125” diameter of the two throats of the throttle body (don’t know the exact measurement), and by the 350 cfm of positive displacement pumping accomplishing by the engine. The velocity pressure (pressure required to accelerate air to a specific velocity) of 7000 fpm is 1.3 psi. The static pressure or friction losses along any reasonably aerodynamic pathway that is only about 2.5 ft. long are going to be small compared with this. So the strategy would be to avoid any unreasonable pressure drops.

Looking closely at the SVX intake system, I see 4 sources of unreasonable pressure drop. The first is the abrupt transition from the filter box to the throttle body. The second is the small radius of the two turns in the intake tube. The third is the corrugation of the intake tube. The fourth is the potentially unaerodynamic transition from the single intake tube to the two throats of the throttle body. I’ve never looked up inside that little plenum, but I’m guessing that there are no internal vanes.

The secret to good high velocity air flow is to get the air up to velocity smoothly, not abruptly and then to keep that velocity up and working for you. So, the transition from the filter box to the MAF should be a longer smoother transition from a rectangular filter to the round 3” diameter tube. Think long rectangular to round funnel. Then, the intake tube should be smoothed out and the radius of the bends should be made as long as possible. There’s no reason to increase the diameter of the tube as the air is already going 7000fpm and you want to keep it at that velocity, because the cross sectional area of the throttle body throats is approximately the same as the MAF. The intake tube should split, however with a good aerodynamic splitter and individual 2+” diameter tubes should run to each throat of the throttle body. These tubes could be very short, only an inch or so, but what is important is that the transition from a single 3” diameter tube to the two 2+” throats should be as smooth as possible.

I really don’t think we are getting any resonance effects upstream of the throttle body. I think the resonant benefits of velocity stacks and ram manifolds are pretty much limited to individual cylinder air pathways. In the combined intake pathway, we are looking at a pressure pulse frequency of 18,000 hz.

All this said, I would doubt that the static pressure drop across the current intake system is more than 1 psi, so we are talking about maybe dropping 0.5 psi of pressure drop. This decrease in pressure drop would increase the mass flow into the engine by about 3-4%. Not much, but maybe worth 6-8 hp.
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  #57  
Old 11-20-2005, 02:15 PM
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Quote:
Originally Posted by shotgunslade
Thinking about pressure drop on the intake system. The primary cause of pressure drop at high RPM is the pressure required to accelerate the air to a velocity of approximately 7000 fpm. This velocity is necessitated by the 3” diameter of the MAF and by what appears to be the 2.125” diameter of the two throats of the throttle body (don’t know the exact measurement), and by the 350 cfm of positive displacement pumping accomplishing by the engine. The velocity pressure (pressure required to accelerate air to a specific velocity) of 7000 fpm is 1.3 psi. The static pressure or friction losses along any reasonably aerodynamic pathway that is only about 2.5 ft. long are going to be small compared with this. So the strategy would be to avoid any unreasonable pressure drops.

Looking closely at the SVX intake system, I see 4 sources of unreasonable pressure drop. The first is the abrupt transition from the filter box to the throttle body. The second is the small radius of the two turns in the intake tube. The third is the corrugation of the intake tube. The fourth is the potentially unaerodynamic transition from the single intake tube to the two throats of the throttle body. I’ve never looked up inside that little plenum, but I’m guessing that there are no internal vanes.

The secret to good high velocity air flow is to get the air up to velocity smoothly, not abruptly and then to keep that velocity up and working for you. So, the transition from the filter box to the MAF should be a longer smoother transition from a rectangular filter to the round 3” diameter tube. Think long rectangular to round funnel. Then, the intake tube should be smoothed out and the radius of the bends should be made as long as possible. There’s no reason to increase the diameter of the tube as the air is already going 7000fpm and you want to keep it at that velocity, because the cross sectional area of the throttle body throats is approximately the same as the MAF. The intake tube should split, however with a good aerodynamic splitter and individual 2+” diameter tubes should run to each throat of the throttle body. These tubes could be very short, only an inch or so, but what is important is that the transition from a single 3” diameter tube to the two 2+” throats should be as smooth as possible.

I really don’t think we are getting any resonance effects upstream of the throttle body. I think the resonant benefits of velocity stacks and ram manifolds are pretty much limited to individual cylinder air pathways. In the combined intake pathway, we are looking at a pressure pulse frequency of 18,000 hz.

All this said, I would doubt that the static pressure drop across the current intake system is more than 1 psi, so we are talking about maybe dropping 0.5 psi of pressure drop. This decrease in pressure drop would increase the mass flow into the engine by about 3-4%. Not much, but maybe worth 6-8 hp.
'Slade,
So, you have your CFD model up and running yet? Here's what the intake manifold looks like where the TB bolts up (It's not this smooth in stock form )



Note: the EGR system feeds up both halves of the intake flow just inside the TB mounting flange (look at the lower part of the picture to see how the EGR porting runs)


I agree with you regarding the flow. I think everything you've noted is a reflection of engineering compromises that resulted from packaging the EG33 in a fixed engine bay volume. Move the MAF too far from the air box and you'll end up with a "trampoline" dynamic motion effect unless you add a support strut up to the MAF from the frame rail.

I've got air box pressure port measurements taken from a port above the air filter (engine side of the flow) at different speeds. Would this info help you in your modeling efforts? The only caveat is that I've got a true 4" diameter ram air system feeding the stock airbox with a "Green" filter in the air box.

-Bill
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Last edited by SVXRide; 11-20-2005 at 02:18 PM.
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  #58  
Old 11-20-2005, 03:15 PM
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Quote:
Originally Posted by shotgunslade
Thinking about pressure drop on the intake system. The primary cause of pressure drop at high RPM is the pressure required to accelerate the air to a velocity of approximately 7000 fpm. This velocity is necessitated by the 3” diameter of the MAF and by what appears to be the 2.125” diameter of the two throats of the throttle body (don’t know the exact measurement), and by the 350 cfm of positive displacement pumping accomplishing by the engine. The velocity pressure (pressure required to accelerate air to a specific velocity) of 7000 fpm is 1.3 psi. The static pressure or friction losses along any reasonably aerodynamic pathway that is only about 2.5 ft. long are going to be small compared with this. So the strategy would be to avoid any unreasonable pressure drops.
Slade what about installing an electrical air ram device, it would compensate all the loss you are talking about... isn't it?
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  #59  
Old 11-20-2005, 06:45 PM
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SVXride:
We're probably not talking about changing the throttle body or the MAF cross sectional area, so, we'd really like to know the pressure drop between the airbox and the throttle body butterfly. Can you measure pressure at the little plenum where the plastic snorkus connects to the two throttle body throats? I was going to say we could use manifold pressure, but unless the engine is fully loaded at 6000 rpm, it won't be WOT, so there will be some unknown pressure drop across the partially open butterflies. If we knew the pressure drop between the airbox and the throttle body inlet at any given rpm, we could calculate the air flow based on the rpm, then calculate the velocity pressure based on the airflow, then, the rest of the pressure difference would be dynamic and frictional losses in the snorkus. Those, we might be able to do something about.

I agree with you, that the reason the aerodynamics were compromsied was packing the intake pathway into a constricted space, and making provisions for servicing (the corrugations).

As far as the CFD, its on my list. I'm going to have to sneak it into the queue. We're so busy right now, my CFD people are backed up for a couple of weeks, and I'm fielding internal emergency complaints from my partners. I'm probably going to have to draw it up and bring in the drawing, because dumping the actual unit I removed from my car on somebody's desk is not the most discrete way of going about getting an analysis done.

Silver Spear:

I think the problem we are looking at here is complicated the really high velocities in the inlet tube. Some vane-axial fans have discharge velocites of 7000-8000 fpm, but inlet and outlet configuration can change the required power to deliver a specific mass flow at a specific pressure by a factor of 2 or more. The problem is that you have already utilized a static pressure drop to get your air stream up to velocity to get through the MAF. The smartest thing to do is to keep that velocity and guide that high velocity stream smoothly and directly into the throttle body inlets. It is all about keeping the momentum of the air stream. Kind of like driving on the track.
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  #60  
Old 11-20-2005, 07:44 PM
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Quote:
Originally Posted by shotgunslade
SVXride:
We're probably not talking about changing the throttle body or the MAF cross sectional area, so, we'd really like to know the pressure drop between the airbox and the throttle body butterfly. Can you measure pressure at the little plenum where the plastic snorkus connects to the two throttle body throats? I was going to say we could use manifold pressure, but unless the engine is fully loaded at 6000 rpm, it won't be WOT, so there will be some unknown pressure drop across the partially open butterflies. If we knew the pressure drop between the airbox and the throttle body inlet at any given rpm, we could calculate the air flow based on the rpm, then calculate the velocity pressure based on the airflow, then, the rest of the pressure difference would be dynamic and frictional losses in the snorkus. Those, we might be able to do something about.

I agree with you, that the reason the aerodynamics were compromsied was packing the intake pathway into a constricted space, and making provisions for servicing (the corrugations).

As far as the CFD, its on my list. I'm going to have to sneak it into the queue. We're so busy right now, my CFD people are backed up for a couple of weeks, and I'm fielding internal emergency complaints from my partners. I'm probably going to have to draw it up and bring in the drawing, because dumping the actual unit I removed from my car on somebody's desk is not the most discrete way of going about getting an analysis done.
'slade,
now you're talking I'll have to talk to Mychailo about getting him to lend me his digital manometer again. Last time I used it I was just concerned about what the ram air set up was doing, thus the single measurement port in the airbox. What I can tell you from that test series is that I didn't see any "ram" effect until I got the car over 40 mph (surprising? no....).
Let me see if I can scare up a spare snorkus...probably easier to rig a variable flow rate fan up to one end and instrument the inlet and outlet...
-Bill
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