• Register Today It's free! This box and some ads will disappear once registered!

  • We are aware of the issue with our internal search engine and we will be bringing it back online shortly. For now please use the Google search bar near the top of each page. Thanks, Rick
^^Searches ExplorerForum.com^^

valve opinions


jd4242

Explorer Addict
Joined
October 15, 2008
Messages
10,809
Reaction score
285
City, State
va beach
Year, Model & Trim Level
92explorer&94 ranger
So just wanted to see what everyone thinks or feels about larger valves. Numbers are just a reference, I have a spare head and will be chopping it up soon to get exact numbers..

So this is more towards the ohv and being FI.keep in mind the ohv has very small valves and I will be stroking it and running 4" pistons.now lets say you have .200 of clearance for the valves to go larger.what would be best for FI and the fack my motor will be larger and stock is super small.

So would you
A-increase the intake valve .200 and leave the exhaust the same?
B-increase the exhaust .200 leaving the intake the same?
C-increase both .100?
D-increase the intake larger say .150 and smaller exhaust increase .050(or any other equal number)
E-increase the exhaust larger say .150 and smaller intake increase .050 (or any other equal number)

What whould you do and why??;)
 


Join the Elite Explorers for $20 per year. Gets rid of the ads! New $5 per month "try out" option.

Explorer Forum has probably saved you that much already, and will continue to save you money as you learn how to diagnose fix problems yourself and learn which modifications work without having to experiment on your own. Elite Explorer members see no advertisements, no banner ads, no double underlined links, can add their own profile photo, upload photo attachments in all forums, and Media Gallery, create and save more private Conversations, and more. Join Today. Your support is greatly appreciated.




Dono

347 V8 Limited turbo
Elite Explorer
Joined
February 18, 2009
Messages
5,281
Reaction score
545
City, State
Winnipeg, Manitoba
Year, Model & Trim Level
00 Limited V8
Basing this on nothing other than off the cuff thinking, Id increase both the same amount, keeping the ratio of valving the same.

Maybe we could look at some performance heads, check the intake/exhaust size ratio and try to copy it?
 




jd4242

Explorer Addict
Joined
October 15, 2008
Messages
10,809
Reaction score
285
City, State
va beach
Year, Model & Trim Level
92explorer&94 ranger
Basing this on nothing other than off the cuff thinking, Id increase both the same amount, keeping the ratio of valving the same.

Maybe we could look at some performance heads, check the intake/exhaust size ratio and try to copy it?
Well that's what I was thinking but things change little for FI.Tom recommended just increasing the intake (A option) but the exhaust is so small and it just didn't make sense to me.my machinist said typically for fi you would just increase the exhaust but he would suggest (C or D) seemed he was leaning towards ""D""
 
Last edited:




colintrax

Elite Explorer
Joined
July 16, 2009
Messages
2,751
Reaction score
40
City, State
Georgia
Year, Model & Trim Level
97 XLT
With the exhaust already being smaller I'd increase both. Like Dono said increase them the same amount
However I have no experience building car engines so take my opinion lightly
 




jd4242

Explorer Addict
Joined
October 15, 2008
Messages
10,809
Reaction score
285
City, State
va beach
Year, Model & Trim Level
92explorer&94 ranger
With the exhaust already being smaller I'd increase both. Like Dono said increase them the same amount
However I have no experience building car engines so take my opinion lightly
Originally this is what I was planning but honestly ill probably do what ever my motor man says too after we cut the head up.just looking for opinions..

Anyone else??:)
 




Carguy3J

Well-Known Member
Joined
June 21, 2008
Messages
1,527
Reaction score
0
City, State
North East New Jersey
Year, Model & Trim Level
'99 4dr. XLT SOHC A4WD
Find some books by a guy named David Vizard. I think one of the titles was "How to build horsepower"

Very good fundamental engine theory stuff.

With the boost, the intake is already getting a little "help", so you might want spend a little more effort on the exhaust side, to get all the extra gas volume back out.

Looking at some combustion chamber pics you posted elsewhere, I don't see how there is any room for bigger valves. They look like they are pretty close to touching already.

You also have to consider that those larger valves may end up being "shrouded" by being closer to the chamber walls; possibly negating any flow gains due to size. You would almost certainly need to do porting work in the chamber, to unshroud the valves. If you're going through all this effort and expense, you might as well spend the money on a really good 5 angle valve job, to get most out of those bigger valves.
 




jd4242

Explorer Addict
Joined
October 15, 2008
Messages
10,809
Reaction score
285
City, State
va beach
Year, Model & Trim Level
92explorer&94 ranger
Find some books by a guy named David Vizard. I think one of the titles was "How to build horsepower"

Very good fundamental engine theory stuff.

With the boost, the intake is already getting a little "help", so you might want spend a little more effort on the exhaust side, to get all the extra gas volume back out.

Looking at some combustion chamber pics you posted elsewhere, I don't see how there is any room for bigger valves. They look like they are pretty close to touching already.

You also have to consider that those larger valves may end up being "shrouded" by being closer to the chamber walls; possibly negating any flow gains due to size. You would almost certainly need to do porting work in the chamber, to unshroud the valves. If you're going through all this effort and expense, you might as well spend the money on a really good 5 angle valve job, to get most out of those bigger valves.
There definitely is room and HUGE gains have been reported. Obviously this is not a shot in the dark type of thing.just looking for other opinions, everyone has one and love to explore it;)
 




Carguy3J

Well-Known Member
Joined
June 21, 2008
Messages
1,527
Reaction score
0
City, State
North East New Jersey
Year, Model & Trim Level
'99 4dr. XLT SOHC A4WD
There definitely is room and HUGE gains have been reported. Obviously this is not a shot in the dark type of thing.just looking for other opinions, everyone has one and love to explore it;)
Good to know there is room. Bigger valves was definitely something I had thought about, when I was asking about porting/modding the 98tm heads. A quick look kinda squashed that thought, but that's good news if they will fit.
 




jd4242

Explorer Addict
Joined
October 15, 2008
Messages
10,809
Reaction score
285
City, State
va beach
Year, Model & Trim Level
92explorer&94 ranger
Good to know there is room. Bigger valves was definitely something I had thought about, when I was asking about porting/modding the 98tm heads. A quick look kinda squashed that thought, but that's good news if they will fit.
Definitely will fit, just few that will pay $38 a valve and or do the research to find out how big you can go.or pay for the services to go that big,""if"" you can call it big..lol
 




jd4242

Explorer Addict
Joined
October 15, 2008
Messages
10,809
Reaction score
285
City, State
va beach
Year, Model & Trim Level
92explorer&94 ranger
So maybe I misunderstood Tom..maybe he said just exhaust, kind of hard to understand some times once we get to rambling.

There appears to be a difference in turbo and sc setup for valves also.there is also a balance you typically want to keep.we all know that typical motors use a smaller exhaust valve because heated air has a higher velocity and is leaving at about 30x pressure.intake its denser air and uses vacuum making it harder to get sucked in..

Well typically you want a larger exhaust valve to allow the added pressure from a FI to escape, especially true in a turbo setup as your adding some restrictions.but for sc it appears that depending on the ratio of the valves and boost levels you may want to increase both if not having the exhaust increased more than intake tho.but this also depends on your exhaust setup and intial valve size.if you have a free-flowing exhaust with no back pressure it doesn't scavenge as much so in theory it acts as it has a larger exhaust valve.so this may be why its ok to increase both the same amount.

But my guy seemed to think the intake was just so small that a increase of larger intake and smaller exhaust may be best.he really didn't go into details but assume he may have thought the exhaust just needed a slight increase as I got a really free flowing exhaust plus I going to run cut outs.I have a feeling he thinks I'm stacking boost being from the intake side and didn't have as much issue getting the gasses out.guess ill need to ask him to go into more details.

Being I feel both are so small and don't think I'm stacking boost I'm still leaning towards increasing both the same if not increasing the exhaust slightly larger as I'm going to be increasing boost so that alone should help the intake side..

Wooo my head hurts..so many variables:(
 




jd4242

Explorer Addict
Joined
October 15, 2008
Messages
10,809
Reaction score
285
City, State
va beach
Year, Model & Trim Level
92explorer&94 ranger
Ok jist got off the phone with my motor guy.he went into a little more details and has changed what he said now that we went into details.
Some numbers and reference

4.0 ohv.
Intake 1.70
Exhaust 1.35

5.0
Intake 1.78
Exhaust 1.54

As you can see the ration of the 4.0 is low for a normal engine of its size.he also didn't know the amount of boost I'm running. He now thinks it would be best to increase the exhaust as much as possible and slightly increase the intake, also thinks im crazy for boosting it that high but assured him everything is getting forged....he suggested .05 on the intake and .150 on the exhaust. Said this would bring the ratio up to about a stock 5.0, would make it (I-1.75 & E-1.50) he feels pretty confident that those would fit but said if I still want he will cut up my spare head and see if he can go larger on the exhaust but wouldn't suggest any larger for the intake.

I may save my money from having him cut the head up and just do a test fit at the sizes he suggested in my spare head.looks like the direction I'm going;)

Anyone else have any suggestions or comments? ?
 




Dono

347 V8 Limited turbo
Elite Explorer
Joined
February 18, 2009
Messages
5,281
Reaction score
545
City, State
Winnipeg, Manitoba
Year, Model & Trim Level
00 Limited V8
Wow, this is really tough.

Have you thought about talking to a custom cam grinder?
A custom cam would change things dramatically also. You would be able to alter valve heights, durations, and the timing of the events.

This would mean that they could recommend what valve sizes to use, and make a cam to better enhance the characteristics of the valves for boost.
 




jd4242

Explorer Addict
Joined
October 15, 2008
Messages
10,809
Reaction score
285
City, State
va beach
Year, Model & Trim Level
92explorer&94 ranger
Wow, this is really tough.

Have you thought about talking to a custom cam grinder?
A custom cam would change things dramatically also. You would be able to alter valve heights, durations, and the timing of the events.

This would mean that they could recommend what valve sizes to use, and make a cam to better enhance the characteristics of the valves for boost.
I did at one time, being they have to grind the cam to gain the extra lift so going any larger wasn't recommended.I showed my guy the specs on the cam last time and he felt it was a pretty good setup, forget what he said but think it had to do with the over lap.plus good lord a custom cam just isn't in the budget, its already outa control. Ill run it by him again just to see what he says as far as new setup though, hopefully he won't wanna change it:(
 




Carguy3J

Well-Known Member
Joined
June 21, 2008
Messages
1,527
Reaction score
0
City, State
North East New Jersey
Year, Model & Trim Level
'99 4dr. XLT SOHC A4WD
Ok jist got off the phone with my motor guy.he went into a little more details and has changed what he said now that we went into details.
Some numbers and reference

4.0 ohv.
Intake 1.70
Exhaust 1.35

5.0
Intake 1.78
Exhaust 1.54

As you can see the ration of the 4.0 is low for a normal engine of its size.he also didn't know the amount of boost I'm running. He now thinks it would be best to increase the exhaust as much as possible and slightly increase the intake, also thinks im crazy for boosting it that high but assured him everything is getting forged....he suggested .05 on the intake and .150 on the exhaust. Said this would bring the ratio up to about a stock 5.0, would make it (I-1.75 & E-1.50) he feels pretty confident that those would fit but said if I still want he will cut up my spare head and see if he can go larger on the exhaust but wouldn't suggest any larger for the intake.

I may save my money from having him cut the head up and just do a test fit at the sizes he suggested in my spare head.looks like the direction I'm going;)

Anyone else have any suggestions or comments? ?
Interesting..... If you're feeling charitable, I for one, would love to see a cross-sectional view of one these heads, showing the size/shape of the intake and exhaust runners. I don't have a head to sacrifice, or a band saw to cut it up.

I'm curious how you will fit larger valves. Is that available "room" you speak of, just the measured gap currently between the stock valves, or does this involve "moving" the valves, relative to the their current position within the head? (ie, offset boring the guides/ new offset seats) If this is the case, how are you planning on dealing with the need to offset the valve-end of the rocker arms? Being that they are shaft mounted, I can see one-off customs being insanely expensive.

On the valve sizes, you list 1.78I and 1.54E as the stock 5.0 sizes, but then you talk about using 1.75I and 1.50E valves. Are those also stock sizes for something, or otherwise readily available? Or are they expensive totally custom made?
 




Dono

347 V8 Limited turbo
Elite Explorer
Joined
February 18, 2009
Messages
5,281
Reaction score
545
City, State
Winnipeg, Manitoba
Year, Model & Trim Level
00 Limited V8
Just stand there, turn your wallet upside down, and shake.

On one hand I read a n/a cam with not too much overlap is the best for boost, then on the other hand I read a custom cam can do wonders for a boosted motor. I really have no clue what to say. I would think that the most lift possible and the least overlap would be best for boost. Read square cam lobes in top this. That is kind of what the 422 cam tries to accomplish.

No clue. Im learning from you.
 




jd4242

Explorer Addict
Joined
October 15, 2008
Messages
10,809
Reaction score
285
City, State
va beach
Year, Model & Trim Level
92explorer&94 ranger
Interesting..... If you're feeling charitable, I for one, would love to see a cross-sectional view of one these heads, showing the size/shape of the intake and exhaust runners. I don't have a head to sacrifice, or a band saw to cut it up.

I'm curious how you will fit larger valves. Is that available "room" you speak of, just the measured gap currently between the stock valves, or does this involve "moving" the valves, relative to the their current position within the head? (ie, offset boring the guides/ new offset seats) If this is the case, how are you planning on dealing with the need to offset the valve-end of the rocker arms? Being that they are shaft mounted, I can see one-off customs being insanely expensive.

On the valve sizes, you list 1.78I and 1.54E as the stock 5.0 sizes, but then you talk about using 1.75I and 1.50E valves. Are those also stock sizes for something, or otherwise readily available? Or are they expensive totally custom made?
Its all custom. Here have a read.these were the heads I was going to buy but he did .100 on both valves and he used the cheaper Manley valves that are not made for boost so I didn't buy them..pictures and flow numbers are in the thread:salute:



http://www.explorerforum.com/forums/showthread.php?t=239196
 




Carguy3J

Well-Known Member
Joined
June 21, 2008
Messages
1,527
Reaction score
0
City, State
North East New Jersey
Year, Model & Trim Level
'99 4dr. XLT SOHC A4WD




jd4242

Explorer Addict
Joined
October 15, 2008
Messages
10,809
Reaction score
285
City, State
va beach
Year, Model & Trim Level
92explorer&94 ranger
Just stand there, turn your wallet upside down, and shake.

On one hand I read a n/a cam with not too much overlap is the best for boost, then on the other hand I read a custom cam can do wonders for a boosted motor. I really have no clue what to say. I would think that the most lift possible and the least overlap would be best for boost. Read square cam lobes in top this. That is kind of what the 422 cam tries to accomplish.

No clue. Im learning from you.
Yea I don't remember the 422 specs or have them right in front of me.do remember it basically was doing that, getting the most lift with small over lap.a lot goes into a cam design so I'm sure if I supplied all my info a better one could be made but how much better compared to the cost..
And my wallet has been EMPTY for years now:( sad when you call or go to get new parts they just ask you.....want us to put it on your card and I don't have to hand them a card:mad:

It seems like we both are learning from each other and others on here as well.that's the best part, I love the knowledge and discussion on here even if what I think is wrong!! Lol
 




jd4242

Explorer Addict
Joined
October 15, 2008
Messages
10,809
Reaction score
285
City, State
va beach
Year, Model & Trim Level
92explorer&94 ranger
Read these books. Seriously. I promise, your mind will be blown:
http://www.ebay.com/itm/like/350439091166?lpid=82
http://www.ebay.com/itm/How-to-Buil...and-Inta-/301030709765?_trksid=p2054897.l4276

I know the second one says "carburetors", but there is alot of intake/head information as well.
Yea my old man has a whole room of books.he use to build motors and race dirt tracks, where I grew up basically. But a lot has changed from those days and this is my first FI motor, FI just confuses him nowadays.all the motors I've built I've built to run on juice (nos) but I was into street racing and track.it was easy to hide and probably the best bang for your buck.I did A LOT of time in jail for racing and my girl at the time got pregnant and made me sell all my cars, this was YEARS ago:(
 


Join the Elite Explorers for $20 per year. Gets rid of the ads! New $5 per month "try out" option.

Explorer Forum has probably saved you that much already, and will continue to save you money as you learn how to diagnose fix problems yourself and learn which modifications work without having to experiment on your own. Elite Explorer members see no advertisements, no banner ads, no double underlined links, can add their own profile photo, upload photo attachments in all forums, and Media Gallery, create and save more private Conversations, and more. Join Today. Your support is greatly appreciated.




QueenCitySleeper

Active Member
Joined
February 23, 2012
Messages
294
Reaction score
0
Year, Model & Trim Level
'99 Sport
Sounds very promising power wise. So let me get this straight, there are NO off the shelf valves that can be modified to fit? Custom made vavles are what's keeping me away. Well that and having custom made forged pistons and rods. I've done some looking but your route (all custom built) seems to be the only way to make this motor strong enough for mean boost or a big shot. Keep the great info a coming!!
 




Similar threads

Top