Torque Torque

[cheapthrills 0]

i'll be picking up a 1905 MI engine D6C shortly, theres a standard intake but no exhaust manifold with it.

i'm debating whether to go for increased bhp..., but perhaps more importantly, for me anyway is to try and increase the lb/ft figures significantly, particularly in the low/mid range, ideally without sacrificing too much from somewhere else.

am i asking for the impossible?

any thoughts? bearing in mind i dont want to get into aftermarket ecu's, throttle bodies, turbos etc

what are the best options for manifold combinations, throttle body, timing/overlap and such?

also can anyone explain a bit about tuned lengths and injection pulses, how would altering the injectors position in relation to the ports affect the outcome?

 

i know theres a lot of questions there but any pointers would be appreciated

 

 

andy

Edited March 28, 2007 by cheapthrills

[smckeown 1]

i'll be picking up a 1905 MI engine D6C shortly, theres a standard intake but no exhaust manifold with it.

i'm debating whether to go for increased bhp..., but perhaps more importantly, for me anyway is to try and increase the lb/ft figures significantly, particularly in the low/mid range, ideally without sacrificing too much from somewhere else.

am i asking for the impossible?

any thoughts? bearing in mind i dont want to get into aftermarket ecu's, throttle bodies, turbos etc

what are the best options for manifold combinations, throttle body, timing/overlap and such?

also can anyone explain a bit about tuned lengths and injection pulses, how would altering the injectors position in relation to the ports affect the outcome?

 

i know theres a lot of questions there but any pointers would be appreciated

 

 

andy

 

you said you don't want to get into TBs but then say your interested in tuned lenghs and differing injector position ??

 

With regards to power increses, look up petert's reground cams on this forum

[brianthemagical 1]

best way will be to sell your mi and get an 8v turbo.

 

tuned lengths are too do with the distance's between pressure changes in inlet and exhaust. i can't remember how to spell his name but someone beginning with smk, with an n somewhere, made a big point about it recently and used variable length inlet trumpets when at the rr. without bodies your probably limited as to what you can do.

 

i think injection pulses are to do with the time the injector is kept open. the fuel pressure is constant(ish) and the size of the opening in the injector is constant so the variable is the time there open.

 

hope thats of some help.

[smckeown 1]

i can't remember how to spell his name but someone beginning with smk, with an n somewhere, made a big point about it recently and used variable length inlet trumpets when at the rr.

 

yes here's my topic covering my research and exploits in this area

http://forum.205gtidrivers.com/index.php?s...12&hl=going

cheers

SMKwithanN

[dee205 3]

You'll be talking about Sean's thread here

 

Tuned lenghts are talked about when using tb's. The closest thing on a standard induction is getting a shortened manifold which a few people on here use. Some say it gives better low down torque some differ.

Messing about with the injector position and stuff like that on a standard induction is probably pointless as it would work out cheaper to get tb's and management with better results.

 

Try a Cat Cam inlet. Nothing but good reports from people on here who use them. PeterT also does inlet cams.

 

 

Damien

[cheapthrills 0]

heres a quote from Martin@PRD

"Driven, owned and built a few Mi16 over the years the best far set up was a standard rebuilt mi16 with 0.020 thou skim to the head, increased over lap with under and over sized Tensioners, the right cam sprockets, mapped fuelling and ignition (not piggy back) on the standard inlet manifold with a tweaked throttle body.

 

By best the far nicest Mi16 driving experiences I have had, it pulled so strong all the way up the rev band with still the mi16 pick up at 4k. If I was going to do another Mi16, this is what I would do, then stick an inlet cam in it."

 

this is kind of what i'm looking for, a way to optimize the engines pulling power without resorting to major surgery. i know that standard management is very limiting and if i do decide to go ballistic a decent ecu will probably be my first stop.i keep reading about the 'flow potential' of the standard MI, i just want to realise a bit of that with good induction/exhaust and better timing before i bankrupt myself in the hunt for bhp.

 

the whole thing about pulse tuning is a bit of a red herring without controllable injection and spark, but as Dee mentioned the variation in torque is there when you cut the standard mani, i suppose the only way would be to test a number of them cut to different lengths to find what youre after.

[28CRAIG 2]

Have a read of THIS these engines give a good amount of torque.

[stux 0]

Hi

In my opinion it is very hard to unleash extra torque in XU9J4 especially in low/mid range. I think the best way for You to go is high flow ported head, 4-2-1 exhaust manifold, and 4inlet and 2exhaust cam pulleys.

TB’s without a plenum probably will ruin torque in low/mid range.

[taffycrook 2]

Before you go out and buy, or start doing any work to you engine think about what torque is and how you can increase it.

Torque is force, and is directly linked to engine size and VE.

So to increase torue you either increase engine size or VE.

If you want to keep std'ish you need to increase the VE on an mi this is not easy as it is very good at gas flow as std.

Major restrictions are AFM, inlet manifold and I am sure exhaust manifold after a point. Once you reach the flow limit of a part the whole thing is held back by that part.

The inlet cam mod works well, proven many times now but I did one of the first in this country which was tested on a dyno. Good gains at the top as well as increased torque almost everywhere but does lose out a fraction low down.

I have tested short inlet manifolds as I used to make them, they do not increase torque but place the point of max torque slightly higher in the rev range and give slightly more power as a result.

Your best bet is to buy vernier pulleys and set the cam timing to give the best torque across the biggest rev range, this can be done with the cat inlet cam and will give the best result for your situation, explain the requirement to the RR and reap the rewards.

BTW max VE on an engine is the point of max torque so the closer you can stay to max VE for longer the more torque you will have.

[TKH 0]

Torque is nothing without RPM. RPM is nothing without torque. If you have both you have POWER. Just look at the 407; The less powerful of the 2ltr petrol engines and more powerful diesel have about the same power but the diesel has something like twice the torque. But the diesel is not any faster. Also guess what one takes less gear changes? No its note the diesel. Its the petrol by a long shot. So to conclude torque on its own has nothing to do with how a par pulls or how fast a car goes or accelerated. But if you really really dont wanna rev you engine more there is no replacement for displacement. But boost will get you close too.

[bales 1]

Torque is nothing without RPM. RPM is nothing without torque. If you have both you have POWER. Just look at the 407; The less powerful of the 2ltr petrol engines and more powerful diesel have about the same power but the diesel has something like twice the torque. But the diesel is not any faster. Also guess what one takes less gear changes? No its note the diesel. Its the petrol by a long shot. So to conclude torque on its own has nothing to do with how a par pulls or how fast a car goes or accelerated. But if you really really dont wanna rev you engine more there is no replacement for displacement. But boost will get you close too.

 

Course torque makes a difference to how fast you accelerate, it is torque at the wheels that accelerates the car which is a function of the gearing. Diesels don't accelerate as fast as petrols even with all the torque because by the time it reaches the wheels it has been multiplied down by such an extent by the gearbox due to the short powerband that it will have no more at the wheels than a lesser petrol engine.

 

This is one of those subjects that everyone argues about but it really isnt that complex.

 

As taffycrook said torque is a direct function of the VE or how much air/fuel you can cram in, nothing else. It can be improved by better ignition and burn etc...but at the end of the day its just how big a bang you get.

[Dom9 2]

XU10 crank for 2045cc and high compression!

[B1ack_Mi16 67]

XU10 crank for 2045cc and high compression!

 

XU10 crank will de-stroke it an give less than 1900cc's

[cheapthrills 0]

what i had in mind was to take a standard MI and using readily available parts, maybe with small mods try to find the best combination to give the motor more oomph below 4000rpm without losing the top end.

improve low/mid range relative to peak bhp if that makes sense

i've read that the typical inlet mani length (road car) is tuned to give decent pickup at low revs at the expense of all out power

what happens if you increased the length of the mani to hopefully provide more grunt, could you find a way to compensate with cams/timing without leaving a big hole in the power curve

or alternatively make some kind of variable flow manifold(secondary throttle plate??), narrow at low revs and opening at high revs, dont ask me how to make it. but would it work?

 

edit to say the engine is recently rebuilt so i dont want to start changing cranks, reboring etc

Edited March 29, 2007 by cheapthrills

[Mattsav 1]

If you want the power to come in earlier then use both the inlet and exhaust cam of Catcams 4900526.

 

The shorter seat duration of the exhaust cam helps the low down power.

[petert 615]

The shorter seat duration of the exhaust cam helps the low down power.

 

I'd argue that it's more desirable to use the standard exhaust cam and advance it to approx. 0.065"@TDC with that much inlet timing. Too overlap pollutes the idle quality and wastes fuel unnecessarily.

[Dom9 2]

XU10 crank will de-stroke it an give less than 1900cc's

 

I knew this was the wrong week to give up booze and fags - Damnit!

[cheapthrills 0]

I knew this was the wrong week to give up booze and fags - Damnit!

 

is it ever a good week to give them up?

 

 

right so, after trawling through a load of previous threads it seems the best combo i've come up with so far using standard management is as follows

 

inlet cam - catcam or petert stage 1

0.5mm copper headgasket

no.4 inlet pulley & no.3/2 exhaust???

still not sure about inlet mani... will the pulley change compensate for a shortened manifold in the torque stakes? or better to leave it standard assuming i can squeeze it under the bonnet?

4-2-1 exhaust