Outer Limits 4x4 Board

hi again
how would i improve my cruising speed on a highway .. what modifications would i need to do
would getting my extractors lower the rpm when sitting on 110km/h ?
currently when on 100km/h its about 3200rpm if i remember correctly .... in fifth gear ?
would extractors lower this rpm ?

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jabboo

Extractors won't alter RPM at all - with the same engine, only a gearing change or tyre size change will affect RPMs at a certain speed.

Gearbox is expensive & unlikely -
Diff Ring & Pinions are just as unlikely - you have 5.29:1's at the moment. 5.57:1's are available from the Auto Feroza but these will make your RPMs higher - lower gears would need to be custom made or an axle swap done.
Tyre Size - this is the easiest & best option. Going to 235/75's or 30x9.5's ( Yes Dave, we know this is not letter of the law legal ) will drop your RPMs at the same speed - but remember your speedo will be out. So you will still show 3200RPM at 100kmh - but you will be actually doing more like 110kmh !!
Also remember though that the manufacturers choose the tyres & gearing to match the engine power & torque. If you drop the gearing the engine has to work harder to push it along up hills etc. So the Extractors / Exhaust help the engine develop a little more power / torque to make up for the loss in larger tyres -
Like everything 4wd - it is one big catch 22

Hope this helps - Mike H.

Thanks Mike for the extra legal info

I've got a question Jabboo- why would you want to lower the RPM? Four cylinder engines are designed to rev higher than a six or eight. They have a different power / torque curve and need the lower gearing to get the engine revving where it can operate efficiently. The redline is 6500RPM, so even 4000RPM is hardly straining the engine.

As Mike has said you'll need to change the gearing to change the RPM at a given speed- this will mean (if you lower the RPM through higher gearing or larger tyres) that the engine will struggle up hills. You'll need to change down gears more often..... you'll lose every drag off the lights .... It will basically feel like you've lost a lot of power.


Just my thoughts on it all......

hell... even at 6,000 rpms she doesnt strain! i've gone in 3rd gear, 6,000 rpms and held a steady 65 mph, passing EVERYONE one a 6% grade hill climb! i love how she sounds while chuggin up that hill, and everyone else is struggling to maintain some steady speed, and i jus go "whooosh" right by em....

SimplyPV wrote:hell... even at 6,000 rpms she doesnt strain! i've gone in 3rd gear, 6,000 rpms and held a steady 65 mph, passing EVERYONE one a 6% grade hill climb! i love how she sounds while chuggin up that hill, and everyone else is struggling to maintain some steady speed, and i jus go "whooosh" right by em....

right before the engine went BOOOOM!!!

stumped wrote:

SimplyPV wrote:hell... even at 6,000 rpms she doesnt strain! i've gone in 3rd gear, 6,000 rpms and held a steady 65 mph, passing EVERYONE one a 6% grade hill climb! i love how she sounds while chuggin up that hill, and everyone else is struggling to maintain some steady speed, and i jus go "whooosh" right by em....

right before the engine went BOOOOM!!!

I was about to write that myself- but thought, no, that's cruel!

hey now be nice to me, when she went boom... she was pullin a 1,700 lbs trailer.... i had done this many times before without the trailer.. guess it wss jus a bit too much.......

jabboo wrote: how would i improve my cruising speed on a highway

Buy a fast car!

thanks for all your comments
i think its just cause i dont like the note it plays with the standard exhaust plus i think there is a hole in it somewhere near the muffler i can feel come air escaping at one of the joins.
so extractors here i come

By the way, read Murcod's thread re full exhaust system...

Also btw, if you're tempted to go for a pod type airfilter, I'd recommend the K&N over the unifilter. Even though I've been pretty careful about maintainence of mine...regular cleaning and oiling, there was still an unacceptable amount of fine dust getting through it. I've now gone back to the original paper filter until I get around to getting a hi-flow foam filter for the original unit and a snork.

Other things you can do are to have your cam reground...just have 'em knock the backs off the lobes ...should cost only a coupla hundred if you're capable of taking it out and reassembling yourself, you can also try advancing the timing a bit and running Premium Unleaded Fuel. Just listen carefully for pinging, and back the timing off a bit if you notice it happening.

There are other things you can do, like running a bigger throttle body on the inlet, or you can modify your existing one...again, I think there's a thread somewhere on that.

Depending on what type of wheelin' you do, you can also take the airbox off...the black plastic thing right on top of the motor...that should also give you a bit of extra mid and top end grunt, but at the expense of low rpm torque.

Jabboo if you're going to do the exhaust you'll get even more noise than a serviceable factory standard system. For some reason the Hurricane extractors make mine sound like a boxer engine (think Subaru WRX - minus the turbo noises unfortunately ) With the rear section done it is very loud- so get the biggest muffler you can squeeze under there.

The pod filter will also make it louder. As AJ said be careful if using one off road. (I swap back to my factory canister if I'm going 4WDing where it's dusty.)

Another way to gain more power is to install an electric thermofan. Just make sure you fit the biggest one you can.

Hey Murcod, how is your beast going with the complete system?? Is it worth doing the rear half, or do ya think is better with just extractors?

AJFeroza wrote:Also btw, if you're tempted to go for a pod type airfilter, I'd recommend the K&N over the unifilter. Even though I've been pretty careful about maintainence of mine...regular cleaning and oiling, there was still an unacceptable amount of fine dust getting through it. I've now gone back to the original paper filter until I get around to getting a hi-flow foam filter for the original unit and a snork.

I wish I'd seen this earlier.... I had a K & N drop in filter in mine with 10,000 k's use I could have taken out..... would have cost you a beer at the local....

I still say don't waste your money on the rear section (or maybe it's just the muffler I've got on?) I have lost a lot of torque down low (ie under 3000rpm), but it will now happily rev out to 6000RPM.

So, if you rev the ring out your Feroza all the time you'll probably like it...... Maximum power would have increased, but the power curve has suffered at low revs. I put the K&N back on yesterday and tried out my favourite hill, from 25km/h it reached the same speed at the same spot- just under 60km/h - as I was getting with the standard rear section.

I'm researching a new rear muffler at the moment, hopefully something that's quieter and flows better. Has anyone got any suggestions? I was thinking something like a Flowmaster 60 series?

flowmasters and cherry bombs are pretty good david, but they tend to be a bit loud.... they flow good but also provide good back pressure as well. a well designed unit in my opinion. i will fit a cherry bomb that i've been holding onto for a while after i get my extractors fitted. speaking of which, theres a mate i was workin with on the problem of hurricanes not fitting lhd ferozas... problem solved! they now fit! i have yet to do this myself, but so far my buddy (jojo) hasnt had any complaints and has noted more torque as well as noise... checkout the pics below to see what we figured out to do and what he went ahead with.

here are 2 more close ups.....

So the pics are of JoJo's Feroza? It must have been fun bending/cutting? the two pipes and getting them around to that angle!

Mine has a straight thru exhaust with 2 hot dog mufflers.
its absolutely deafening, and has no acceleration whatsoever under about 3000rpm!!!

It was a backyarder job by the look of it.

If youre gonna do it, then i suggest do it properly, so that you actually get some gains from it, rather than just making double the noise......

I agree.... get the biggest muffler that you can possibly fit under there.... and don't go over 2" piping.....

jabboo wrote:hi again
how would i improve my cruising speed on a highway .. what modifications would i need to do
jabboo

Spend some money and find a six speedto bolt in. Would be a bit of work involved but could be could be worth it if you do alot of cruising.

I read over in the daihard forum about feroza/charade gearboxes and that the gear ratios are interchangable. I posted up a thread asking wheather this is correct or not and yes it is right

so they are interchangeble ?
whats there 5th gear like compared to ours ?
would it be much trouble to change it over ?

Check these links out for the answers u want and then do the calculations
http://dairally.net/daihard/chas/Gears/Gears.htm & http://dairally.net/daihard/chas/MiscCa ... lDrive.htm


James