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-   Suzuki Jimny, Sierra & Samurai Forum (https://www.suzuki-forums.com/forumdisplay.php?f=156)
-   -   Threoly header and exhaust pipe size (https://www.suzuki-forums.com/showthread.php?t=52141)

mobile3 05-20-2012 03:23 AM

Threoly header and exhaust pipe size
 
Hi guys
Sorry for my language

I have samy 92 with G13BA engine and carb system and I plan to swap later to 1.6 8v engine.
I have Doug Thorley headers and want to get high-end horsepower more than low-end torque especially for G16A engine
So, my question: what is best exhaust pipe size if I have modified Yukon muffler?

Most recommendation I found is between 1.75in and 2.25in.
But how?
Doug Thorley comes with 2.5in collector. if exhaust pipe size smaller than collector size, will make "Reducer" in opposite direction. I'm right

please correct me if I'm wrong

More info, my samy is for off-roading in desert only.

Thanks in advance

caseyjones955 05-20-2012 04:41 PM

I researched this quite a bit, when I bought my Samurai it came with the 1.6 16v EFI engine installed. It has 2.25" from a Thorley header through a Flowbastard and out the back. Not only is it obnoxiously loud but it is a bit soft down low. I asked several questions and asked of the Gurus at Low Range Off Road and Trail Tough and got the same response every time without variation.

1. Gains with a header are very minimal, if any, but mine came with one.
2. 2" all the way, this held true for 1.3 or 1.6.
3. Use a quieter performance muffler and an after market cat conv. I used the exact part numbers recommended by a guy at Trail Tough. The same part numbers he was using on his own rig, then went on Ebay, it IS a nice setup. It flows and sounds decent, seems to flow plenty good enough for this lil' 1.6L

I am somewhat new to Suzuki but in general and my experience with VW and other makes has shown me that the 8v engines are better for low end grunt where the 16v engines are a little softer down low but stronger from mid range on up. It comes down to the charge velocity as it enters the cylinder through a single instake valve vs freer flowing 2 valves. The Suzuki 16v are EFI and are more detailed to install in a Samurai.

If this 8v vs 16v theory is NOT correct for Suzuki engines for some reason I hope someone will chime in and correct me.

A question: Have you considered using a Mazda rotary engine? Conversion isn't that bad, its been done a number of times and top end is pretty wild while low end is weak, esp for non turbos. Actually not sure I want to go that fast in this short wheel base vehicle. I have messed a bit with rotary power and do love them but they are thirsty and power delivery is way off for off road use.

Will you drive this on the street? I wonder if your going to give up a whole bunch of drivability for a very small gain at high revs with a Suzy engine.

Tony

mobile3 05-21-2012 02:32 AM

Thanks tony for reply

Actually, I already have 1.6 8v engine needs to remove from another vehicle, I do not plan to do swap yet.

You don't think
1.6 8v engine + ISKY POWER CAM + modified header and exhaust = will change torque curve that will shift power from Low-Mid to Mid-High

Quote:

Originally Posted by caseyjones955 (Post 329721)
Will you drive this on the street? I wonder if your going to give up a whole bunch of drivability for a very small gain at high revs with a Suzy engine.

I as I said before, this samy for off-road only so I don't mind for drivability;)

Bahdal

Boxcar 05-21-2012 05:45 PM

Why would you want to destroy the low end torque curv on an off road only rig???????
...Boxcar....

mobile3 05-22-2012 01:53 AM

Because I don't needed at all except when I am in the road to desert

Boxcar 05-22-2012 11:03 AM

You may be confused. Low end torque is as necessary in the desert as it is in the woods.
The 8 valve 1600 will make descent amounts of torque and better spool over a 1300 in stock format. A nice mid range cam, 2" exhaust system, the Corolla 1600 carb Or the my side 40mm conversion and proper tire size for your gearing, and you should be good to go.
Don't overlook the little things like, plug wires ( I run 9mm wires ), Good plugs,
Valve timing, Ignition timing, etc.
We run my Sammy in the woods mostly, but take a trip every year to the Alvord desert
and to China hat. Trust me , without the bottom end that my mill produces. I'd be stuck out there still.
While the Samurai is a very capable off road rig. It is by no means a desert racer.
Running wide open out across the desert with Leif spring suspension will destroy your
zuke and your back......If that is your intension. I'd be researching 4 links and long travel suspension systems, as well as some pretty substantial axle upgrades........Boxcar...
http://i1109.photobucket.com/albums/...car2/003-3.jpg

mobile3 05-23-2012 04:12 AM

I appreciate Boxcar your reply

I disappoint from Threoly header. I test Threoly header and stock header without exhaust pipe in street out of my city.:eek: i know.. i know ... crazy

Two tests:
A. from 30K/H to 80K/H
B. from 60K/H to 100K/H

The Result: by average = no one win :huh:

So, my test to figure out where my power band and where to shift it for better result in desert (not racing but need to accelerate as u can and climb the sand)

But because I don't see any difference, I will go back to stock header and exhaust
And install electric Weber. Then I will try again with Threoly header

If I understand things wrong or you have difference result, please clear that to me.

mobile3 05-23-2012 04:58 AM

Quote:

Originally Posted by Boxcar (Post 329900)
The 8 valve 1600 will make descent amounts of torque and better spool over a 1300 in stock format. A nice mid range cam, 2" exhaust system, the Corolla 1600 carb Or the my side 40mm conversion and proper tire size for your gearing, and you should be good to go.
Don't overlook the little things like, plug wires ( I run 9mm wires ), Good plugs,
Valve timing, Ignition timing, etc.
[/IMG]

Wow nice info

how much you expect from 8 valve 1600 engine with these mods?

Rhinoman 05-23-2012 06:38 AM

Quote:

Originally Posted by caseyjones955 (Post 329721)
I am somewhat new to Suzuki but in general and my experience with VW and other makes has shown me that the 8v engines are better for low end grunt where the 16v engines are a little softer down low but stronger from mid range on up. It comes down to the charge velocity as it enters the cylinder through a single instake valve vs freer flowing 2 valves. The Suzuki 16v are EFI and are more detailed to install in a Samurai.
Tony

8V and 16V engines can't be compared directly it depends on other factors such as cam design and valve sizes, also a 4-valve engine has a more efficient combustion chamber and can therefore run higher compression.
Suzuki's 1.6 16V is a very sofly tuned engined, it makes the same power and torque as the 8V up to around 3500rpm. The torque on the 8V starts to drop off over 3500 at a much faster rate than the 16V. I did have a dyno comparison but it was lost in a hard drive crash a few years back.

caseyjones955 05-23-2012 11:55 AM

When I did work with VW 8 valves torque was damn nice for the size engine but getting top end required to much modification and still couldn't blaze past rows of RVs and Harleys the way a 16v could (especially in similar state of tune). But I digress, I realize I'm not in VWland anymore :( All the gurus have told me that the Suzuki 16v is superior to the 8v in every respect. This is consistent with my opinion based on test drives before purchasing. The 8v is an easier install but the advantages end there.

That being said I'm not entirely convinced an 8v wouldn't do the job you want it to do. If cost is an issue AND you already have access to an 8v than it seems like a good choice. I'm going to x2 what Boxcar said about importance of torque. If I were doing what your doing I would probably save the $$ and use the 8v. There is a real limit to how fast I want to go in a short wheel base, leaf spring vehicle on inconsistent terrain. I had mine up to 75 on smooth pavement before I took it out of service again and even that was a pucker factor of about 3.

Tony


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