Rob_DOHC

iTrader: (4)

This is Karlos's old spec car which it turns out is identical to my spec minus karlos's low compression pistons



I just thought is was funny, because here is mine: with t285t2 cam (same as karlos) and standard bottom end running essentially the same boost etc.


My car suffers from boost drop off and a spike i think due to the scummy bleed valve it has fitted, however clearly having standard comp ie higher pays dividends regards to when the car comes on boost and torque level. Not relevant any more as both cars have different spec just thought it was funny.

Rob,

Rob_DOHC

iTrader: (4)

Also annoying that my car couldn't hold power and especially torque at rpm would be handy if you could fill me in on the rest of your old spec karlos.

if any one else wants to chip in and post up graphs of a similar power out put or spec it would be good, would love to see a few with different cams or turbos etc.

Rob,

Karlos G

iTrader: (4)

We have different cams Rob!
Mine is not the 285T2 it's the 285T which has a much nicer profile favouring low/mid power rather than everything at the top end like the T2....

Your high comp does make more power earlier even running a laggy 285T2! Which is why i'm staying standard CR on my current build, low comp is not needed until your over at least 300bhp
Mine hit peek boost 17psi @ 4000rpm then gradually dropped down to 10psi @6400rpm (limiter), when did you make peek boost and what did it drop to?
If our RPM readings are accurate of course........ which they are probably not! lol

Interesting though why you make peek BHP @ 4800 and I made mine right at the limiter?!
All I can think of is that maybe my turbo was in better condition than yours, or you had some other restriction at high RPM's?

My full spec was....
Stock T3
Accralite 1.5mm low comp pistons on stock rods and crank
Piper 285T
K&N Cone
Magnex Exhaust
Ahmed Chip'd ECU
Ported head
No bleed valve, actuator and Amal only.

xr2wishy

iTrader: (2)

can i be the first to point out that Rob had 0.5psi more of boost too, it would make a bit of a difference.
higher compression always gives more power over a low compression engine, it's just a case of the componants taking the strain, which is why the economic costing goes towards lower compresion for more room for error and reduced strain.
in an ideal world we'd want really high compression to get more power out, but the costs of this can rise substantially.
another example is that i had a leanburn non turbo 1600cvh with a 0.5mm over bore running 13psi of boost and that was pulling just under 200bhp (197fwhp IIRC), same setup but with standard rst pistons didn't pull anywhere near the same power (wish i'd have a RR session on it to see the difference)
there are articles all over the internet where this is discussed in more depth.

JamboRS

no hassles my end with lag compared to this high comp engine,its all in the speccing and set up,mines low comp stg 3 head,should be a lag monster by passionford standards

Chip

iTrader: (3)

Much prefer the low shape of the graph for the 182 figure!

If given the choice of those 2 engines, I would be picking that one

Karlos G

iTrader: (4)

Jambo I could have put money on you posting up that graph when people talk about low comp vs high comp! lol
Is that a 1600cc and what turbo is it? 21psi by 3000rpm is impressive!!
EDIT: Why is the dyno set on 4wd?? What car is it??

But...... bottom line on LC vs HC is that HC will always make more power if no other variables are changed.... to the point of Det.

Why is that Chip, surely Robs engine will be much more responsive than mine (going by the graph shape)?
Or just because of how it spikes and then drops dramatically?

JamboRS

just proves that low comp isnt the lag monster everyone thinks,eauns cossie wae mega low comp and t4'd and was on full boost before most t34's
thats my old engine mate,yes its a low comp 1600,with AVA specced big valve head and a stage 3 t3,cam was a custom newman on that graph,ive got a pipert2 graph but it wasnt as repsonsive as the newman

alan runs cars in that mode,dunno why,he knows his dyno but it doesnt affect power,all cars are ran in that mode im sure

Karlos G

iTrader: (4)

I'm just asmazed TBH, in 500rpm it goes from 6psi to 21psi and makes an extra 82bhp!!

JamboRS

powers at the wheels mind

Karlos G

iTrader: (4)

Yes I know!!!

JamboRS

u know me too well,i dont quote anything but wheel figs

Rob_DOHC

iTrader: (4)

Ohhh interesting stuff on the cam Karlos, i read t28* and just made the rest up lol,

my turbo is pretty fucked and i don't think the bodgetastic bleed valve is helping things but your graph did look nice pulling to the top.

To be honest the car drives/drove very nicely like that ignoring the high rpm torque drop off (which i think is due to knackered parts) i think looking at the two graphs if you weren't full throttle etcetc at high rpm the higher comp engine would actually drive better around town, ie @ 2800rpm high cr was making 65bhp and 125ft.lbs where as low comp even with mild cam was only making 50bhp and 100ft.lbs and @ 3200 high cr is 80bho 135 ft.lbs compared with 110ft.lbs and 70bhp.....

A nice graph would actually be karlos's top end and my bottom end, especially if it didn't have the t285t2 fitted, @ karlos i think it hit full boost rather quickly (even with the 2wd turbo) like at 35-3800 rpm however the spike was massive and the drop off quick lol, also i think totd quoted max boost at the spike which i don't really understand?

Point being that with the correctly speced and non knackered components high comp really is worth it, and more to the point karlos's new engine with standard compression should be something rather nice. Jambo your graph looks quality, but i cant help thinking max boost would be reached earlier and power/torque would look better with a higher compression ratio.

Rob,

Rob_DOHC

iTrader: (4)

i take it by low shape you mean bhp? lol

Karlos G

iTrader: (4)

I think thats what he means, but too me that just looks laggy compared to yours! lol
I could understand liking the top half, as you said if we cut and shut the graphs that would be quite a nice drive for a stock T3!

Karlos G

iTrader: (4)

Hopefully my new engine will be sweet! Pistons should be here end of the week I think so can get things moving!!

I think really the point is that until your breach around 300bhp (fly) there is no need for low comp so why gain any lag at all if you dont need to?
Jambo's graph is excellent for what anyone would say should be a laggy engine (going by his spec), fuck knows how it's like that, but as you say Rob with high comp it could have been even better!!!

Rob_DOHC

iTrader: (4)

ye should be pretty nice, the engine is coming out of mine soon now most of the snow has gone, im not aiming for massive power, but i think on a mild cam with standard compression, a slightly worked head, rebuilt 2wd cosworth turbo with standard exhaust housing, proper boost control and efi should see a very nice torque curve hopefully better than mine and 200 brake @ 6000 with out dropping off etc, would be nice if i didn't loose as much torque @ higher rpm etc

I hate to say this on a forum where turbos are the love but you really cannot beat a good sc setup,



I bet that goes like shit, and at any rpm lol

Karlos G

iTrader: (4)

Essentially Rob thats the same spec as me! lol
Your 2WD T3 is almost identical to my stage 2 (.36/55), stock CR, Flowed head, AVC-R boost control, MS2 EFI management, although I have a lazy-arsed off the shelf Newmans cam which is very very similair to a T2
But that will be the only thing making me even slightly laggy, everything else I have spec'd for response not top end BHP.
Would be nice to make around 200wbhp

Whats that graph from??

Rob_DOHC

iTrader: (4)

supercharged ls1 engine,

To be honest if mine has 155 brake at the wheels 160-180whp and a really responsive, torquey set up/curve would be fine for me

Im going to be tight and use a blue printed but otherwise standard bottom end tho, pistons will be fine, the con rods are being shot peened with all casting marks removed. But to be honest i know the con rod is the engines weak point, but at 20-21psi of boost and a 6k rev limit i can't see them breaking with me driving it, sure they will let go if its treated as a 7000 rpm car but its not and wont be..... higher rpm actually exerts higher loads on pistons and conrods than a higher boost pressure.......

Talking of nice shiny forged bits have your pistons come yet?

I was considering asking newmans to grind some custom cams to kent cvh32-33 spec, think if i got more than one done a few guys on hear would like them??????? bit of a group buy really, as the 33 seems to be a very good cam minus is wear properties and the newman profiles seem not to be spot on but with much better materials used...

Rob,

Karlos G

iTrader: (4)

Rods have been known to let go as low as 190bhp but others say they are ok at 270bhp so I think as long as you dont go silly revs as you say they will be fine, Mahles are good for 300bhp+ so there is no worries there.
My pistons should be here end of the week I think!

Always worth asking Newmans, see what they will do! If I had known the off the shelf RST cam was as lazy as it is I would of asked them for sure!!
Yeah the 33 or the 285T are both nice profiles from what i've been told.

Rob_DOHC

iTrader: (4)

oh well, we'll see.... if the conrods let go it will be entirely my fault, just got a few projects at the moment so funds need to be split amongst them this year, so forged rods and pistons can wait on the rst.

JamboRS

andy r on here had same spec engine except he had ava managment and fancy inlet and exh fanimolds and made something silly like 270+@wheels and full bosst by 2800,think that was nearer 2 bar of boost

also i had a ava custom newman cam,one of the first newman cams to be in a rst,id say if i was on a piper or kent id prob not have made the power so early,the head is the key to gettin power from an rst,if you spec that correct along with a proper cam then it can be made to be as laggy as a std comp rst.

mine would have breezed 250@wheels if i went for ava management,it was just the shitty mfi holding it back,that mide range spike of 21/22 psi could have been held right to the limiter.in the end i got fed up and broke it
itching for a new rs of some sort,hopefully be in one by the summer

Karlos G

iTrader: (4)

Full boost by 2800rpm @ 2bar!
I bought an off the shelf Newmans cam, if i'd realised how lazy the profile was and that NMS do a custom one I would of gone for that, as you say it makes a big difference to spool up times.

JamboRS

he was running throttle bodies and ava inlet and exhaust fanimolds,that brought the power band down lower as well as helpin it rev to 7500+rpm,think rev limiter was set at 8k.ava modded the turbo and he was running a 3" bore exhaust aswell as a custom newman and rs500 intercooler,thing is ava customised the cam to the spec they wanted and newman ground it from a blank,you cant buy these custom cams unless you give newman the spec you want.heres a pic,it was awesome

JesseT

Rob, have you tried retarding the cam you have?

Rob_DOHC

iTrader: (4)

No, as the car doesn't have an adjustable pulley at the moment plus listening to the engine i think its lobes have gone south lol, what benefit would retarding the cam timing have?

Rob,

Karlos G

iTrader: (4)

Retarding the cam timing would give your more up top but at the cost of low/midrange power/response.

Rob_DOHC

iTrader: (4)

Digging this up again! Stripped my head a few weeks ago and found that the cam fitted wasn't a t285t2 like the paper work said it was! and had no markings on at all so all i can assume is that the cam was standard, making higher comp look a little better above.

Rob,

rsmark86

iTrader: (3)

damn i what one of them ava manifolds .... and what is that inlet.. as im gunna run same sort of spec as im looking for my car to hold 25psi so unsure what it will peak at

Rob_DOHC

iTrader: (4)

Not sure, think it could be using modified pulsar tb's??????

Rob,

JamboRS

both custom made inlet and exhaust fanimolds

Rob_DOHC

iTrader: (4)

what are the throttle bodies mate?

JamboRS

im not 100% sure what throttle bodies they used