What is everyones opinion on this,with MAD using 8.4-1 on a 800+ engine what will this mean?

Is low comp going to be a thing of the past for big bhp or is it the reliable choice still?

This is not a smart arse/slag tuner postIts a genuine question as if MAD pull this off low comp will be the thing of the 80's.

Please Please see this as a genuine post,i am fed up of being called a troublemaker,i know the cynical will see it as trying to say other tuners are wankbut that couldnt be further from the truth.I have always been told by some std and higher comp is the way to go for the YB but it was equalled by the folk that said low comp is the way.

Is this the dawn of a new era?I am a fanatic ref the YB and its development.

 

if you can get away with high comp and releve some lag at the same time as ganing torque it would be rude not to lol

 

I guess different tuners will always have there own opinion and ways of doing things.

Benni.

 

Phil,

Mark has been saying for a while now that the only thing good about the 80's was the music. low comp isnt the way forward now apprently

 

Rich i have always said higher comp was the way but was always shot down,i beleive MAD had a chat with JG because of what i said,maybe wrong i am not out to cause trouble.I know not alot but i can get advice from the pro's due to my business.

 

Phil

I have only had 2 conversations with people at JG and these were renting there dyno to shut up the doubters about the dyno I use, then about the 99 block a year ago nothing else,
But when you start hearing about companies going up on comp ratio it starts you thinking and then analising your data on your engines/mapping then tweaking spec's to suit,
This has been ongoing for over a few years but I have taken a carefull aproach so it has been going up over that time and more data collected,
Not anytype of spec can take a big increase in comp there are a few hidden details that make it work also,
So saying your trad T4 engine can go from 7.2-1 to over 8-1 is not always correct there are some changes that need to be made also to make it work well.

Mark

 

Go to bed Mark or is the little fella keeping you awake lol

Mike

 

Is it not partly engine geometry, combustion chamber design and piston speeds being reduced compared to running std rods/stroke which helps?

Cams, big turbos etc and moving the power band north all make a difference I would imagine. The big power evos are all up at these comps - do they run the same sort of pistons speeds etc?

At a guess Rod's is not std on any of these.

 

i think the length of the rods will play a big part

 

Mike,

He usually blames me with my PM`s.........

 

Then just give in and tell him to order the best turbo for your car lol,

It's about time you modded it a bit more then sold it to somebody else isnt it lol

Mark you taking care of my car, it aint moved far has it...

Mike

 

Not moved yet just need to be sure to move it

Mark

 

I am giving you plenty of time l have a bloody wedding to pay for and a Porsche to shift, plus l am in the states this winter so will be topping up your DVD collection and shopping for bits lol

Mike

 

Phil

The other side of the coin will be he's not actually running it that highIam sure the odd tuner would be saying this,
I may post a picture of the piston one day but its not that trick a shapeits the other bit that make most of the diff.

Mark

 

length of piston and rod can be change so tht it dont push to hard on the cylinder in its stroke due to anglu would realy like to now what hadland has done because his is loner throw he gets alot of the bad bits back

 

It's all in hand Mike, as for selling, i might even keep this one for a year or more.. really hooked on this old taxi for some reason..

 

Simon Norris i think uses the theory build a high power N/a engine then turbo it

He built a cossie a few years back that i had the pleasure of being in with higher comp than std went really well with over 600bhp too

With the more controllable ecus there are now and the big roller bearing turbo's which flow more helps keep the temps down hence higher comps and more ignition can be used for more power

Only if you know what your doing !!and there are only a few that do

Paul

 

as i understand it lowering the comp ratios releaves the stresses of engine componants at a sacrifice of power and torque which can be compensated for by upping the boost pressure.
however if the engine is really well built a high compression ratio can be used and more power can be released, therefore a lower comp engine needs more boost to produce a certain power, thusly the higher comp engine has more power potential and more torque than the lower comp engine.
i used to run a high comp engine on a tt setup and at 10psi it was far quicker than 13psi on a low comp erst engine.
it's mainly cost effectiveness that dictates which method gets used.

 

Is it the thickness of the piston crown,or lack of it ?

puddy

 

thickness and construction of the piston crown makes a massive contribution to the running of the engine. the better it can disipate the heat the more advance and power can be obtained.

 

how the worms have turned lol

 

I seem to recall Karl doing a few 8:1 engines with a T4 on it rather than the ussual 7.2:1 or 7.6:1?

Sounded like a nice package as well.

 

Yes karl did a T4 conversion on 8-1,i beleive Jim Green had it done?

Sorry mark if it sounded like i was involved with your higher comp decisions,i remember chatting to you about my 7.9-1 and GT35 and saying that JG says no probs so assumed you spoke to him,but as you say you saw others going up the ratio and figured it was the way and you now proving it!

 

My rallycar was high-comp (although I really can't remember what) and ran 1.9 bar all day long but with restrictor.

Mind you, I loved it as it was soooo responsive and mentally fast up to 100 MPH!

 

err, race fuel, no?

on race gas youd be daft to run in the 7s, no need.

 

it will still be running 700+ on pump mate.

 

how do we know, its not done it yet

until there YBs running as good a powerband or better, on pump gas, and with the same long term reliability (ie long top speed runs etc with no issue), i dont see how anyone can claim its the future and high comp is the way forwards for 250+bhp per litre engines.

 

going from the previous session mate on 7.9-1

I agree reliability is the key but as mark says its been well thought out to provide that.

 

mark is a top tuner, his cars are proven to be the bollocks, but until its proven good in the long term i wouldnt even take gods word for anything.

last engine didnt even make it off the dyno.

 

Fair point.

BUT please be aware if God did give his word to you i would be seeking medical advice.

 

`

 

ive been running plus 250hp in the 9's for 10 years on pump fuel, like ive been telling you for years pal and thats flat out everytime its used, not going to the shops or cruising down the local strip.

 

we can't sum up the whole of an engine with one number (the compression ratio) so why are people trying to!

 

what you on about rod?

whats the magazine or reyland got to do with me?

nothing thats what. and negative and proven in long term are two different things.

i never said it cant happen, might wanna read what i said.

and speaking of that...

I said 250+bhp per litre mate...

 

and i did say plus 250 as well, did i mention 1/2/3/4 litres ?
but i didnt read it correctly !!

 

Good words

 

Time will tell how reliable, The issuse on the dyno last time was head gasket hopefully the change will fix this,
All my engines have been going up on comp for the last couple of years and these have proved very reliable so Rods engine is not to much of a risk on the reliablity side,
We know why the gasket failed and have made other changes also based on what happend,
I have another 2 engines on the go in this spec so Rods will not be the only proving the reliablity at this level.

Mark

 

Here is another data point for you guys.
As you know high comp concept is not new, I chatted to the head engine man for Dick Johnson with his dominating group A sierras.
(Actually he still has the original engine lab they used, with all the cossy bits which is neat)
He said that they felt high compression was the way to go way back then but they never had enough time to research it fully, they worked with the Group A guidelines, and found extra power by other means which was interesting but off topic for this thread.

He went on to say that since that time (sierra group A) he did go down that path and works with high comp engines constantly and talked of the low comp spec as being very old school and something they left behind a long time ago. A lot of WRC work goes his way, which guys mentioned on this thread is high comp work.

His team did a lot of stuff that set them apart from sierras all over the world, I respect his opinion.

 

very interesting

 

Rod you are one sad man Ha ha ...I know you edited it out but was quoted before it was lost!!!!!!!!