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Author Topic: Thoughts on 24v zorts!  (Read 4400 times)

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Offline Tony

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Thoughts on 24v zorts!
« on: October 13, 2008, 00:49:06 AM »
So all you guys with 24v's i wonder what exhausts do you find best?
years ago when i built my first 24v i fitted the standard system and found that was good

since then i have tryed a few aftermarket pipes and i just cant get the performance i used to have with my old system.
i have tryed many things to get all i had, i can get better by reducing the back box size but its still not so good.

i personlay think the standard xr4x4/xr4i system is really well matched to the 24v, less the cats.

yes its small bore compaired to after market but it works well

what do you guys think? is smaller bore better for these 24v engines?
(yes i do know the answers, tell ya later)

tony
« Last Edit: October 13, 2008, 00:50:53 AM by maddoldbugger »



the 24v xr4i auto-0 to 60 in 6.71 secs

Offline capri v8 driver

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Thoughts on 24v zorts!
« Reply #1 on: October 13, 2008, 08:42:14 AM »
i used the 12v downpipes (modifyed to fit the 24v), they go into a 55mm pipe, flowmaster damper, 55 mm pipe over the axle into a 3r racing damper.

at first whit this system, the engine did not reached 90 deg off water temp and it felt slow. after i made a 45 mm restrictor ring in the last damper, the temp went up and so did the power. and less fuel consumption.

i have build and give a helping hand to people that build cobra's whit a 24v, most off them use a bigbore exhaust and custom headers, the one's that went on the roller, they all had less power.

greetz Paul.

Capri V8 Driver.

Offline Tobbelainnen

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Thoughts on 24v zorts!
« Reply #2 on: October 13, 2008, 10:22:30 AM »
I got too big primaries on my headers, 2 1/2 inch from the collectors and backwards, both sides are joint to a single 2 1/2 pipe, 2 1/2 simon muffler in the rear, as for tail pipe I got a 3" bit, the resonance is terrible    My engine does also suffer from not getting warm, I use a stock BOB stat...

BUT I am making propper headers for it this winter, and I do also want to go down in pipe size after the collector....  Would make life easier.....  I have parked the car for the winter now, but I think I need to take it out and try Pauls restrictor method and see what differs in makes...


//Tobbe
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Offline Dave

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Thoughts on 24v zorts!
« Reply #3 on: October 13, 2008, 10:49:23 AM »

Well this is a old one  

How many times has this cropped up on the net  


Well I did think the 24V does need a bit of back pressure but the more I learn about exhausts & cams the more that statement does not make sense.

So I will go with "testing needs to be done in a controlled manner with actual comparable results on a engine running a after market ECU"

Dave

Offline capri v8 driver

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Thoughts on 24v zorts!
« Reply #4 on: October 13, 2008, 12:07:41 PM »
i agree whit dave.

to really put this matter to the test, you have to put the engine on the dyno, and try various exhaust's and back pressures. to really see what the difference is you need to test all exhaust systems whit a stock ecu and a aftermarked ecu and even cam timing and its relation to a exhaust sytem can and need to be tested. this will take many hours on the dyno, and that will not be cheap. not even mentioned the labour involved to test every combination.

you must see a 24v engine combination as a complet package,  its not a 12v, that where ford tryed to reach the emissions norm by slapping cats behind it, different cam, heads, pistons and a different programming off the ecu.

the boa and certanly the bob 24v, all the parts are designed whit emissions in mind in the first place to meet the emission norm back than and later years. and what do we do? the first thing we do is trow the cats and everything thats related whit emission away and use our one parts like the exhaust. you end up whit a package thats not the same as ford designed it. some off our parts work and some don't work whit the 24v. and to really see if our parts that we ad, work, you need to put it on a dyno or rollers.

but from what i have seen whit the cobra kitcars whit a stock 24v and ecu, whit custom headers and big bore exhaust, not one came close to the stock output off the engine on the rollers.

whit my capri, i played whit different size restrictor rings to get the best result. the first thing i noticed was that the engine got hotter and reached his operating temp faster. according to my butt dyno, the capri felt faster and sinds i drove the capri every day, i also had a beter fuel consumption. all that by adding backpressure.
« Last Edit: October 13, 2008, 12:17:27 PM by capri v8 driver »
greetz Paul.

Capri V8 Driver.

Offline Tobbelainnen

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Thoughts on 24v zorts!
« Reply #5 on: October 14, 2008, 07:44:57 AM »
I run an aftermarket ecu on my car, loggin is no problem, so if I do a few pulls on the road from 800rpm up to the limit at 5200rpm in 3th gear,  then I can compare the graphs of the rpm signal, then I should be able to tell if the restrictor did any noticeable differ on my car...  I guess a few pulls is needed to tell how accurate this is. It is possible to place two rpm graphs onto each other so it should be easy to visulize it.....   I can use lambda correction at full load agains my afr table so it will do some minor adjustments, after all it runs on a MAP sensor, so it should be remapped... But the corrections stuff will be good enough for a quick test I think.....

Bad idea or could it give me some useful information?
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Offline capri v8 driver

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Thoughts on 24v zorts!
« Reply #6 on: October 14, 2008, 08:40:10 AM »
you can try it.

i dont know if you logging program can show rpm against time. that would show you the difference in how fast the rpm climbs in a gear, when you make a pull.

a gtech can do this.
greetz Paul.

Capri V8 Driver.

Offline Mik

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Thoughts on 24v zorts!
« Reply #7 on: October 14, 2008, 09:43:48 AM »
A trick that can be used to measure the optimum back pressure would be to fit a SuperTrapp muffler system. These use diffuser discs at the end of the exhaust system. the more discs, the less back pressure.
If this is used on a vehicle which has proven power loss on a dyno, then by reducing the number of discs, a perfect setup can be achieved.
This could also test the effects of back pressure at different speeds and loads.

Mik.

Offline Dave

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Thoughts on 24v zorts!
« Reply #8 on: October 14, 2008, 10:13:03 AM »
Thing is Tobbe yours is the 4.0L.

The compression it runs at & the bottom end in thery should affect the exhaust.


Personnally I think all your doing when your messing with the back pressure is matching the Scorpio's STD exhaust system that the engine was set up for.

Hence why it works best.

But the STD engine has loads of what is mainly emission stuff bolted on it.

Was a auto & is hardly aimed at performance  

However some of that emission stuff can also help performance.

One such thing is the cam over lap.

You can look at it in different ways depending on what your trying to achieve.

Cam over lap in the Scorpio is emission related & when you think about it actually works a bit like a EGR system.

For it work you need a certain back pressure.

Now this sounds like an argument for back pressure but the same kinds of over lap & more can also be used in racing engines to suck in charge with the aid of a well designed exhaust header??????

Already you can see that this could end up with me spending hours trying to explain it all & probabably only confusing everyone  


In short you can talk about this for along time & get no where.

Only way is to test different things in a controlled manner!
« Last Edit: October 14, 2008, 10:32:51 AM by Dave »
Dave

Offline Tobbelainnen

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Thoughts on 24v zorts!
« Reply #9 on: October 14, 2008, 10:52:46 AM »
Quote from: capri v8 driver
you can try it.

i dont know if you logging program can show rpm against time. that would show you the difference in how fast the rpm climbs in a gear, when you make a pull.

a gtech can do this.

I'll try to do something with some old logs tonight and see how it works, if it isn't to much trouble to import the values into mathcad, I'll try that program, it draws much better graphs then excel... Just need to make a graph comparing the derivates of the rpm signals, it will be shown at any rpm what it looks like....

I think that with too big exhaust you get a too slow gas sped allowing the gas to cool down, and dens gas is more work for the engine to push out.... So actually just getting in a restrictor shouldn't do that much on my engine I think, the gas speed will still be slow in the pipes. It is the diameter of the pipes that needs to be smaller.....

As Dave says, this subject will never end, and I will probably only get more confused...  And you are  correct about mine is totally different then a 2.9. I was unbit unclear in my last post, "useful information", I meant for me   And not for the others....
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Offline capri v8 driver

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Thoughts on 24v zorts!
« Reply #10 on: October 14, 2008, 12:00:35 PM »
for the black 5.0 v8, i use a equal length 1 5/8 inch primaries whit 2.5 inch collector. even for the blue capri i use these size header.

i think you need to go down to 1.5 inch primaries whit a 2 inch collector.

i think, for the main time, you still can play whit a restrictor and see what happens.

like dave and i (post 5) already said, you need to test this on a dyno or rollers in a controlled manner to get the best results and to see if the engine package works or not.
greetz Paul.

Capri V8 Driver.

Offline Tony

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Thoughts on 24v zorts!
« Reply #11 on: October 16, 2008, 02:09:45 AM »
well there is a can of worms here!
yes the 24v does need back pressure"
BUT
its no good just restricting a huge pipe!! that doesnt work. and if dave doesnt mind he does have some graphics that show why it doesnt work!

thing is, years ago i got my 24v to give 236bhp  (no egr)and since that i have never been able to get that much, i lost out when i had to change the zorts,

yes i do have a really nice scorpion system on the car and i would swap it for a standard granada one now.

tony

the 24v xr4i auto-0 to 60 in 6.71 secs

Offline Dave

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Thoughts on 24v zorts!
« Reply #12 on: October 16, 2008, 13:19:41 PM »
Yeah it's a complicated thing  

So you been looking at that then Tone  

Well I started doing that for Samol when he got some crap results with his new headers on his 24V.

It has no benefit to me as I am turbo so play by different rules but I thought if I tried to explain things better then it might help people get some good results with their 24V & the development of the engine can move on in the DIY world.

I have not finished yet

http://fordpower.org.uk/forum/index.php?showtopic=5072&pid=33293&st=0&#entry33293]http://fordpower.org.uk/forum/index.php?sh...amp;#entry33293
« Last Edit: October 16, 2008, 13:21:33 PM by Dave »
Dave

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Thoughts on 24v zorts!
« Reply #13 on: October 16, 2008, 17:42:23 PM »
Quote from: Dave


Well I started doing that for Samol when he got some crap results with his new headers on his 24V.

I have not finished yet

http://fordpower.org.uk/forum/index.php?showtopic=5072&pid=33293&st=0&#entry33293]http://fordpower.org.uk/forum/index.php?sh...amp;#entry33293

Hi Dave, I keep looking at that post, but so far no more to chew on, (10th May last entry), time to stop work, and get the playing completed mate,      Cheers Ray

Offline capri v8 driver

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Thoughts on 24v zorts!
« Reply #14 on: October 16, 2008, 19:17:34 PM »
thats a good piece off writing

http://fordpower.org.uk/forum/index.php?sh...amp;#entry33293]http://fordpower.org.uk/forum/index.php?sh...amp;#entry33293

i think, but thats just me thinking, in Tobbelainnen case, he increased the size off his engine to 4.0l, but is using the 24v heads and cam, the flow these heads and cam combination have are good for a 2.9 till 6000 rpm, but to small for a 4.0l, combine that whit a bigger primaries and collectors, and you have a missmatch. i think, he needs to increase the flow off the heads and a beter cam selection to make use off his exhaust system and to get full power out off the engine.

for the 2.9 24v in n/a form, its beter to stay close to the orginal size's off the exhaust system.

but thats just me thinking. i dont have the flow data for the 24v heads, so for me its guessing at this point.

greetz Paul.

Capri V8 Driver.

Offline Tony

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Thoughts on 24v zorts!
« Reply #15 on: October 16, 2008, 20:46:49 PM »
funny,  so many years people have told me i was talking out my arse.
yet along comes dave with some nice pix/graphics and  bingo!!

ok.
one thing we might not have noticed is that ford designed there standard systems to match there engines.
look at a 1991 xr4x4 system and you will see the two down pipes join a pipe thats only slightly larger than the two down pipes, this then goes on to a back box thats really small, infact the backbox is smaller than one downpipe!!!!!!. its basicly a tapered pipe size!!
this was explained to be, the gasses are hot and fully expanded on leaving the engine, they cool and there for loose there mass, hence the tapered exhaust! and you get this
[img]http://i20.photobucket.com/albums/b228/DavidHoward/Folder%201/exhaust3.jpg]http://i20.photobucket.com/albums/b228/Dav...01/exhaust3.jpg[/url]
makes sence doesnt it!

so after saying all this, it explains why i couldnt get the performance of the standard system, resticting the back box helps but its far from ideal.
[img]http://i20.photobucket.com/albums/b228/DavidHoward/Folder%201/exhaust4.jpg]http://i20.photobucket.com/albums/b228/Dav...01/exhaust4.jpg[/url]
no matter how much you baffle this its never going to flow well!!!!

tony
« Last Edit: October 16, 2008, 20:51:02 PM by maddoldbugger »

the 24v xr4i auto-0 to 60 in 6.71 secs

Offline Dave

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Thoughts on 24v zorts!
« Reply #16 on: October 17, 2008, 00:31:05 AM »
Quote from: samol
Hi Dave, I keep looking at that post, but so far no more to chew on, (10th May last entry), time to stop work, and get the playing completed mate,      Cheers Ray

I started that to answer your post but was to busy at the time to finish it also I found that the different ways to work it out don't exactly match each others results.

Anyways now I have visted 11 countries + got my HGV class 1 & 2 I will finish it soon  



I am told a STD BOB head flows about 95 exhaust & 120 inlet CFM which is almost the same as a YB funny enough.

A BOA will flow slightly less I think but I am just guessing.
Dave

Offline capri v8 driver

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Thoughts on 24v zorts!
« Reply #17 on: October 17, 2008, 07:59:30 AM »
Quote
I am told a STD BOB head flows about 95 exhaust & 120 inlet CFM

i hope they flow more than that, even a stock v8 small block e7 head's can flows more than that, whit only 2 valve's per cilinder.
« Last Edit: October 17, 2008, 11:13:28 AM by capri v8 driver »
greetz Paul.

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Offline Dave

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Thoughts on 24v zorts!
« Reply #18 on: October 17, 2008, 09:31:43 AM »
Paul thats Euro spec results

Us spec would be 158.6 Exhaust & 200.4 Inlet.


This would mean that maths wise STD BOB heads & cams can make no more than 350 horsepower N/A

They simply can not flow any more as STD.
« Last Edit: October 17, 2008, 10:21:07 AM by Dave »
Dave

Offline capri v8 driver

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Thoughts on 24v zorts!
« Reply #19 on: October 17, 2008, 10:46:06 AM »
the stock v8 e7 heads have a 150 cfm on the intake, 123cfm on the exhaust. at 0,500 lift. (depending on the year the head is cast)
« Last Edit: October 17, 2008, 11:10:39 AM by capri v8 driver »
greetz Paul.

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caprinut

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Thoughts on 24v zorts!
« Reply #20 on: October 23, 2008, 21:29:18 PM »
yer , you have to consider this, that an engine is a gas pump the kinetic energy we get out of it is a byproduct.

 

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