I believe that split duration is needed on the TIV- PERIOD!
The stock cam was even split duration!
I only use 2 straight pattern cams and both of those I'm experimenting now with a 2.5 degree (5 degree) split on the exhaust side- they are for busses.
I have one cam that has 22 degrees more duration on the exhaust than on the intake! as well a .030 more lift on the intake!
What camshaft
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lmcchesney
- Posts: 135
- Joined: Thu Nov 20, 2003 8:11 am
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Bleyseng
- Posts: 994
- Joined: Fri Apr 21, 2000 12:01 am
Nah, its just that the snorkel on the air cleaner inhibits (chokes) air at high rpms. If you have to run a stock air cleaner for class rules, cut the snorkel off. Look at them, they have a 1 1/2" opening.
The other trick is to run a cold air pipe to the air cleaner so the engine breathes cool air instead of hot engine compartment air.
Vacuum is a function of the motor parts and pieces, it doesn't have anything to do with the air supply problems.
On dyno tests (2000 to 6000 rpms) you usually do it at WOT so that is where the 1hp gain is at without the air cleaner.
Geoff
The other trick is to run a cold air pipe to the air cleaner so the engine breathes cool air instead of hot engine compartment air.
Vacuum is a function of the motor parts and pieces, it doesn't have anything to do with the air supply problems.
On dyno tests (2000 to 6000 rpms) you usually do it at WOT so that is where the 1hp gain is at without the air cleaner.
Geoff
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Dave_Darling
- Posts: 2534
- Joined: Thu Apr 27, 2000 12:01 am
Uhh, you do realize that the 914 harnesses are already being done, right? http://members.rennlist.com/914_wiring_harnessesraygreenwood wrote:I am pushing hard also to finish a few D-jet parts...like some spare brand new harnesses...both 411/412 and 914 style ...
I bet Bowlsby would be able to do 411/412 harnesses (D-jet, at least) if there was enough demand for them, and if he had an example to use. Most of the connectors should be the same, though I'm not sure about the four-pin plug at the relay board end.
Now the MPS diaphragms... We need those!! Get on 'em, man!
--DD
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raygreenwood
- Posts: 11907
- Joined: Wed Jan 22, 2003 12:01 am
A few things. The stock air cleaners...replacing them or leaving them off..as little or no bearing on most of the stock applications. They flow much higher than the TB.
No the injection timing is not adjustable....from the factory. Its not at 180*. Its 165-168 depending on the wear an tear. It also has about 10-15 degrees of dead area between each ramp. The injection timing is also changed when you re-set the ignition timing other than factory...because it changes when you turn the distributor, which iswhy D-jet is so sensitive to timing changes and valve adjustment spec. It also fires injectors in pairs. What do you mean compensated for by where you set the cam?. You do not have those choices with stock D-jet.
Unless I am losing my marbles, you are calculating overlap wrong. There is not that much overlap I don't think. I may be wrong though. I'll calculate it tonight.
Yes...180 HP. But not with D-jet....but its runners yes. Its plenum...with some work....but not the TB combined.
As far as intake versus exhaust overlap...they are the same thing. Yes, longer duration starting at the same opening point as stock...will intrude into the exhaust. Wether this is part intake or part exhaust...or all intake or all exhaust..I'm not sure. I have no stock cams to measures by. Havn't used any in years.
Intake wise...the type 4 Always needed better intake duration. Exhaust wise, it also needed more exhaust for cooling. From the late cam to early cam specs...I think itgot a little of each and some lift.
Velocity is better atomization. Laminar flow has nothing to do with this in an injected engine. That is a venturi principle. It does not apply to injection at all. But...from which perspective have you come to the conclusion that more velocity is less efficiency...and more resistance? It is both true and untrue...depending upon where in the engine is measured from.
Its not important to get the highest velocity...or to keep the lowest velocity. The velocity should range...but smoothly. Its about how the metering is run...and what it requires to keep running smoothly. More later....have to go to a meeting. Ray
No the injection timing is not adjustable....from the factory. Its not at 180*. Its 165-168 depending on the wear an tear. It also has about 10-15 degrees of dead area between each ramp. The injection timing is also changed when you re-set the ignition timing other than factory...because it changes when you turn the distributor, which iswhy D-jet is so sensitive to timing changes and valve adjustment spec. It also fires injectors in pairs. What do you mean compensated for by where you set the cam?. You do not have those choices with stock D-jet.
Unless I am losing my marbles, you are calculating overlap wrong. There is not that much overlap I don't think. I may be wrong though. I'll calculate it tonight.
Yes...180 HP. But not with D-jet....but its runners yes. Its plenum...with some work....but not the TB combined.
As far as intake versus exhaust overlap...they are the same thing. Yes, longer duration starting at the same opening point as stock...will intrude into the exhaust. Wether this is part intake or part exhaust...or all intake or all exhaust..I'm not sure. I have no stock cams to measures by. Havn't used any in years.
Intake wise...the type 4 Always needed better intake duration. Exhaust wise, it also needed more exhaust for cooling. From the late cam to early cam specs...I think itgot a little of each and some lift.
Velocity is better atomization. Laminar flow has nothing to do with this in an injected engine. That is a venturi principle. It does not apply to injection at all. But...from which perspective have you come to the conclusion that more velocity is less efficiency...and more resistance? It is both true and untrue...depending upon where in the engine is measured from.
Its not important to get the highest velocity...or to keep the lowest velocity. The velocity should range...but smoothly. Its about how the metering is run...and what it requires to keep running smoothly. More later....have to go to a meeting. Ray
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raygreenwood
- Posts: 11907
- Joined: Wed Jan 22, 2003 12:01 am
I have been making my own harnesses for years. Harnesses like mine are being made nowhere. The outer covering is cast silicone. Made in a full polyester mold. Its cast around the wiring bundles. Very clean. Totally waterproof. They have all L-jet dual cantilever terminals modified to plug straight up and seal with D-jet. Everything is 10 micron gold plated. I don't use stock D-jet terminals for anything but tailights and wiper unit connectors anymore. These are "0" resistance harnesses. They are aso good to over 450 F continuously because of the jacketing. I have only made 3 of them to date. One long one for a 412 wagon and two short ones for 411/412 sedans. Also, I just added a mod for sequential D-jet.
There would be nothing superior to them (just hard to beat the materials).I have never really planned to sell them, mainly because I'm not interested in wasting time convincing people that these are better harnesses. I don't have time to be in the business of making harnessess. Also....though I have a huge stock of terminals of all types, building a business around them at thispoint would be expensive and difficult. Some are hard to get, though they are not in short supply. Lots of proprietary BS.
But if I were helping someone do FI mods that took critical tuning. I would not do it without using something cleaner and more dependable than the stock harness. The stock connectors are junk. AMP's internal studies show failure rates in as low as 12 cycles on original D-jet terminals. Jeff probably makes the best factory reproduction/replacement harness out there. But IMHO...it also has the same main defects as the factory harness. Good for a resto...bu it will hold you back in the end when the tuning gets intricate. Ray
There would be nothing superior to them (just hard to beat the materials).I have never really planned to sell them, mainly because I'm not interested in wasting time convincing people that these are better harnesses. I don't have time to be in the business of making harnessess. Also....though I have a huge stock of terminals of all types, building a business around them at thispoint would be expensive and difficult. Some are hard to get, though they are not in short supply. Lots of proprietary BS.
But if I were helping someone do FI mods that took critical tuning. I would not do it without using something cleaner and more dependable than the stock harness. The stock connectors are junk. AMP's internal studies show failure rates in as low as 12 cycles on original D-jet terminals. Jeff probably makes the best factory reproduction/replacement harness out there. But IMHO...it also has the same main defects as the factory harness. Good for a resto...bu it will hold you back in the end when the tuning gets intricate. Ray
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raygreenwood
- Posts: 11907
- Joined: Wed Jan 22, 2003 12:01 am
Imcchesney, sorry my answer was so incomplete earlier. I was at work.
Velocity increasing resistance and decreasing efficiency. My question is...where? It matters. The cylinders are drawing a fixed volume. That can only increase or decrease if efficency falls due to...restriction or air density problems (heat etc.). If the runners and plenum are the right size for this engine....what you said ...does not hold true.
At a higher velocity, you will be drawing the same volume of air in at a faster rate...but the same volume per revolution... just the same. Its when the TB...or the plenum...becomes too small to feed that increased rate...that one of them will become a restriction. THAT will be the problem with trying to get 180 HP from a set of runners and plenum not large enough. As I noted earlier, when running at high rpms, the runners are being emptied, they are emptying the plenum, the plenum is pulling in through the TB. this is overlapping alternately on two pairs of cylinders...constantly.
The TB is only a METERING restriction. If its too small at WOT...then it becomes a true restriction.
Properly sized and calibrated, the TB is not a true restriction..because it will be admitting the proper volume of air to replenish the current rpm related cyclic needs of the engine no matter what the throttle opening . This is what I mean by "tension". A constant rate of even vacume..across the necessary range to signal various levels of enrichment...is what is needed. If any chamber is too small...the tension immediately below that increases. The level of tension at the next point of potential restriction upstream...will start to cavitate while trying to supply air above its design limits. That turbulence restricts air ingress at stages below. At some point you effectively get a stall to the air speed as turbulence becomes high enough to literally block incoming air.
My comment on "perspective" means this. Higher velocity and increased flow in a column like the runner and plenum...will be a restriction...if you are PUSHING air into that column. The restriction will be at the bottom end (the valve). Also, resistance will increase from friction alone...as atmospheric pressure on the walls of the runners destroy the boundry layer. Also...I would bet that the runner openings in the plenum...under pressure...would be a restriction...more so than when under vacume. Since it is being drawn in...the restriction will be at the top. But since the TB is not a venturi...it is a variable planned restriction.
And in D-jet...turbulence means poor or inopportune vacume...which means poor fuel metering. That causes poor efficiency fast.
The exhaust is the bottom most tier of the "tension" chain. If its limiting in volume or velocity, things will stack up.
The stock exhaust of a 1.7...though not very efficient in velocity...is excellently sized in volume. This is why..even with poor scavenging characteristics....it runs well on a highly tuned 1.7...with a litle better valve overlap. The valve overlap helps to get more exhaust out...and pull more intake charge in. It only works decent on the 1.7 ..because the exhaust volume is just enough larger to absorb the extra exhaust vented by the overlap. The ERNST version of the stock exhasut...is about 10% larger in volume. That and smoother welds makes for about a 15% increase in exhasut capability. Add a little better lift duration and overlap...and things run well.
Volumetric efficiency is only hurt by velocity...IF... while maintaining that velocity...you are creating too high of a vacuum. That would be the resistance you are thinking of...and hence why I am saying proper sizing is critical.
180 HP with those runners and plenum is entirely possible...but if they are making that with a large displacement engine....then it is technically starving for air. Does not sound very dependable to me....it will run very hot.
Otherwise, they are making it with a very highly efficent small engine whose volume is sized well for the amount of air allowable by those runners and plenum. I mean like everything optimized......extensive head porting. Very custom and well thought out cams....very high compression...very custom exhaust and an awesome ignition system. It to will not be your average street engine or daily driver. It will also be $$$$. I also seriously doubt it would be a 1.7 or 1.8.
When I say 120 HP....among stock sized parts....thats about right. Can you make more? Sure! Looooots of tuning...and some mods. Getting a hair over 100 is not that hard with a 1.7. Yes D-jet can do it. Most FI can. The tuning involved though...is not simply slapping it on and twisting screws. It may be more effort than most would think D-jet is worth. Me...? I'm impressed.
As for the valve overlap...46* thats crank revolutions right?....don't you divide by two for cam degrees? At least thats how I have been thinking of it. I am less worried by exactly where the crank and pistons are at the overlap point...and more interested in how much of each cycle...in tme....each valve is lapping into. I am out of town . I have none of my books in front of me...so I'm lost at the moment.
Velocity increasing resistance and decreasing efficiency. My question is...where? It matters. The cylinders are drawing a fixed volume. That can only increase or decrease if efficency falls due to...restriction or air density problems (heat etc.). If the runners and plenum are the right size for this engine....what you said ...does not hold true.
At a higher velocity, you will be drawing the same volume of air in at a faster rate...but the same volume per revolution... just the same. Its when the TB...or the plenum...becomes too small to feed that increased rate...that one of them will become a restriction. THAT will be the problem with trying to get 180 HP from a set of runners and plenum not large enough. As I noted earlier, when running at high rpms, the runners are being emptied, they are emptying the plenum, the plenum is pulling in through the TB. this is overlapping alternately on two pairs of cylinders...constantly.
The TB is only a METERING restriction. If its too small at WOT...then it becomes a true restriction.
Properly sized and calibrated, the TB is not a true restriction..because it will be admitting the proper volume of air to replenish the current rpm related cyclic needs of the engine no matter what the throttle opening . This is what I mean by "tension". A constant rate of even vacume..across the necessary range to signal various levels of enrichment...is what is needed. If any chamber is too small...the tension immediately below that increases. The level of tension at the next point of potential restriction upstream...will start to cavitate while trying to supply air above its design limits. That turbulence restricts air ingress at stages below. At some point you effectively get a stall to the air speed as turbulence becomes high enough to literally block incoming air.
My comment on "perspective" means this. Higher velocity and increased flow in a column like the runner and plenum...will be a restriction...if you are PUSHING air into that column. The restriction will be at the bottom end (the valve). Also, resistance will increase from friction alone...as atmospheric pressure on the walls of the runners destroy the boundry layer. Also...I would bet that the runner openings in the plenum...under pressure...would be a restriction...more so than when under vacume. Since it is being drawn in...the restriction will be at the top. But since the TB is not a venturi...it is a variable planned restriction.
And in D-jet...turbulence means poor or inopportune vacume...which means poor fuel metering. That causes poor efficiency fast.
The exhaust is the bottom most tier of the "tension" chain. If its limiting in volume or velocity, things will stack up.
The stock exhaust of a 1.7...though not very efficient in velocity...is excellently sized in volume. This is why..even with poor scavenging characteristics....it runs well on a highly tuned 1.7...with a litle better valve overlap. The valve overlap helps to get more exhaust out...and pull more intake charge in. It only works decent on the 1.7 ..because the exhaust volume is just enough larger to absorb the extra exhaust vented by the overlap. The ERNST version of the stock exhasut...is about 10% larger in volume. That and smoother welds makes for about a 15% increase in exhasut capability. Add a little better lift duration and overlap...and things run well.
Volumetric efficiency is only hurt by velocity...IF... while maintaining that velocity...you are creating too high of a vacuum. That would be the resistance you are thinking of...and hence why I am saying proper sizing is critical.
180 HP with those runners and plenum is entirely possible...but if they are making that with a large displacement engine....then it is technically starving for air. Does not sound very dependable to me....it will run very hot.
Otherwise, they are making it with a very highly efficent small engine whose volume is sized well for the amount of air allowable by those runners and plenum. I mean like everything optimized......extensive head porting. Very custom and well thought out cams....very high compression...very custom exhaust and an awesome ignition system. It to will not be your average street engine or daily driver. It will also be $$$$. I also seriously doubt it would be a 1.7 or 1.8.
When I say 120 HP....among stock sized parts....thats about right. Can you make more? Sure! Looooots of tuning...and some mods. Getting a hair over 100 is not that hard with a 1.7. Yes D-jet can do it. Most FI can. The tuning involved though...is not simply slapping it on and twisting screws. It may be more effort than most would think D-jet is worth. Me...? I'm impressed.
As for the valve overlap...46* thats crank revolutions right?....don't you divide by two for cam degrees? At least thats how I have been thinking of it. I am less worried by exactly where the crank and pistons are at the overlap point...and more interested in how much of each cycle...in tme....each valve is lapping into. I am out of town . I have none of my books in front of me...so I'm lost at the moment.
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MattR
- Posts: 66
- Joined: Mon Jan 26, 2004 3:59 pm
This is on the topic of camshafts, so I thought I'd post it here.
Okay, so Im going to tear my 914 apart next weekend and Im ordering parts now so I wont have to wait.
Here is my setup so far:
2.0 L T4
Dual Weber 40s
KB 96mm pistons with stock stroke
stock intake and exhaust valves
stock exhaust and upgraded muffler (PO did this)
my questions is for the cams and followers.
cbperformance.com has eagle cams and followers for like 100 and 40 respectivly, and webcams are 155 and 140 respectivly. I want to make this a daily driver. Is it worth the extra for the webcam? And, which grind do you suggest? If I do go with web, I was thinking the web 494 cut.
Are eagle cams good quality? Or is it worth the insurance for web.
Okay, so Im going to tear my 914 apart next weekend and Im ordering parts now so I wont have to wait.
Here is my setup so far:
2.0 L T4
Dual Weber 40s
KB 96mm pistons with stock stroke
stock intake and exhaust valves
stock exhaust and upgraded muffler (PO did this)
my questions is for the cams and followers.
cbperformance.com has eagle cams and followers for like 100 and 40 respectivly, and webcams are 155 and 140 respectivly. I want to make this a daily driver. Is it worth the extra for the webcam? And, which grind do you suggest? If I do go with web, I was thinking the web 494 cut.
Are eagle cams good quality? Or is it worth the insurance for web.
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Piledriver
- Moderator
- Posts: 22775
- Joined: Sat Feb 16, 2002 12:01 am
Aircooled.net, buy Johns warranteed Web/homebrew lifter mod combo, AND bearings and oil pump, he'll cover the whole shot if things go to hell.
It's at least as good as Web, probably better, and a bit cheaper.
(Someone was just cussing about the lifters Web currently has...)
If you have the bucks, and/or value your time and sanity, please consider ceramic lifters.
Getem/over/done/dont worry about it.
Less can be more. AutoX is all torque...
It's at least as good as Web, probably better, and a bit cheaper.
(Someone was just cussing about the lifters Web currently has...)
If you have the bucks, and/or value your time and sanity, please consider ceramic lifters.
Getem/over/done/dont worry about it.
Less can be more. AutoX is all torque...
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.