high comp vs low comp pros and cons etc what pple think
12-10-2007 | 06:46 PM
#82
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From: barry-south wales
Originally Posted by Bosch_Dealer
...chip you have to get into your head..some tuners actually know what they are doing 
...you are not a tuner yourself so can only go by books..actually try it..you may well lose a few engines to start with but you will get there 
..as i have said horses for courses...if a track car that does a variety of digfferent tracks i'd go 7.5-1 ion pump...on a rally car i'd go 9-1 on race fuel...on a road car i'd go std to 8.5-1 on pump fuel upto 600bhp...on a top speed car i'd go std comp too if race fuel is allowed as you will make more power ..all yb of course.
...you are not a tuner yourself so can only go by books..actually try it..you may well lose a few engines to start with but you will get there ..as i have said horses for courses...if a track car that does a variety of digfferent tracks i'd go 7.5-1 ion pump...on a rally car i'd go 9-1 on race fuel...on a road car i'd go std to 8.5-1 on pump fuel upto 600bhp...on a top speed car i'd go std comp too if race fuel is allowed as you will make more power
..all yb of course.
12-10-2007 | 06:47 PM
#83
Originally Posted by Mark Shead
Rods conrods are 5mm longer than stock and the crank has 6mm longer throw, the piston is standard size but with a 8mm higher pin.
Mark
Mark
What sort of ignition advance do you have at peak torque on your 600bhp 8.0:1 (which to me is still low compression TBH in the grand scheme of things) YB on 98 octane fuel then?
And also where was that torque and how much was it?
12-10-2007 | 06:57 PM
#84
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From: Marlow Bucks
Chip
Not got my laptop with the files at home, But some of the engine I have mapped/biult tend to run between 8 and 14dg ranging from 480ftlb and 550ftlb,
Rods last engine ran 18dg Ign at 2.5bar boost,
I have found so far that running a Cossie down to 8dg does not cause any real rise in EGT the only problem I find is when the intake temp goes in to ign retard you tend to loose lost more power than a large ign angle low comp engine, So the secret is no high temps and my installs dont suffer from this
.
Mark
Not got my laptop with the files at home, But some of the engine I have mapped/biult tend to run between 8 and 14dg ranging from 480ftlb and 550ftlb,
Rods last engine ran 18dg Ign at 2.5bar boost,
I have found so far that running a Cossie down to 8dg does not cause any real rise in EGT the only problem I find is when the intake temp goes in to ign retard you tend to loose lost more power than a large ign angle low comp engine, So the secret is no high temps and my installs dont suffer from this
.Mark
12-10-2007 | 07:47 PM
#85
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From: brum/shropshire drives:- frst / escort cossie
Originally Posted by Mark Shead
Chip
Not got my laptop with the files at home, But some of the engine I have mapped/biult tend to run between 8 and 14dg ranging from 480ftlb and 550ftlb,
Rods last engine ran 18dg Ign at 2.5bar boost,
I have found so far that running a Cossie down to 8dg does not cause any real rise in EGT the only problem I find is when the intake temp goes in to ign retard you tend to loose lost more power than a large ign angle low comp engine, So the secret is no high temps and my installs dont suffer from this .
Mark
Not got my laptop with the files at home, But some of the engine I have mapped/biult tend to run between 8 and 14dg ranging from 480ftlb and 550ftlb,
Rods last engine ran 18dg Ign at 2.5bar boost,
I have found so far that running a Cossie down to 8dg does not cause any real rise in EGT the only problem I find is when the intake temp goes in to ign retard you tend to loose lost more power than a large ign angle low comp engine, So the secret is no high temps and my installs dont suffer from this
.Mark
...So mark
12-10-2007 | 08:06 PM
#86
Originally Posted by GARETH T
rs500 tourcars went ok i would say!
your not talking about technology, the theory of engine design hasnt really changed in decades
name one thing you are doing now, that people wasnt doing 40 years ago
your not talking about technology, the theory of engine design hasnt really changed in decades
name one thing you are doing now, that people wasnt doing 40 years ago
12-10-2007 | 08:29 PM
#87
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Originally Posted by MAD Ade
Originally Posted by GARETH T
rs500 tourcars went ok i would say!
your not talking about technology, the theory of engine design hasnt really changed in decades
name one thing you are doing now, that people wasnt doing 40 years ago
your not talking about technology, the theory of engine design hasnt really changed in decades
name one thing you are doing now, that people wasnt doing 40 years ago
12-10-2007 | 08:47 PM
#88
all i was ever told was need low comp if running massive boost. mines 7.5/1 and stu said exhaust temps wernt an issue at 2.2 bar. my car is at least 225 bhp per litre and i havnt seen my exhaust temps go above 700 degrees on the defi gauge.
12-10-2007 | 10:51 PM
#95
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From: North Korea
Originally Posted by Bosch_Dealer
Originally Posted by MAD Ade
Originally Posted by GARETH T
rs500 tourcars went ok i would say!
your not talking about technology, the theory of engine design hasnt really changed in decades
name one thing you are doing now, that people wasnt doing 40 years ago
your not talking about technology, the theory of engine design hasnt really changed in decades
name one thing you are doing now, that people wasnt doing 40 years ago
The BRM V16 engine was a 1950s supercharged 1.5litre F1 engine and ran 72psi, thats SEVENTY FUCKING TWO PSI BOOST, in 1951
And thats one of tons of examples.
Using cars that run on race fuel is a TOTALLY irrelivant comparison when talking road cars, ive heard many race engine builders and mappers state that with certain race fuels it was nigh on impossible to get the car to det by just turning the boost up and up, the limit truly became internal pressures rather than det, so obv can run muuuuch higher comp regardless.
12-10-2007 | 11:16 PM
#96
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From: Glasgow/Oban
sorry martin, just the number of times Ive seen this kind of discussion on her and knowing the thread could beaccomplished to s sensible end in a page if it wasnt for folk like boschman, and tuners who arent prepared to tell the full story lol.
Each to their own tho!
Each to their own tho!
13-10-2007 | 12:42 AM
#98
Originally Posted by Mark Shead
Chip
Not got my laptop with the files at home, But some of the engine I have mapped/biult tend to run between 8 and 14dg ranging from 480ftlb and 550ftlb,
Rods last engine ran 18dg Ign at 2.5bar boost,
I have found so far that running a Cossie down to 8dg does not cause any real rise in EGT the only problem I find is when the intake temp goes in to ign retard you tend to loose lost more power than a large ign angle low comp engine, So the secret is no high temps and my installs dont suffer from this .
Mark
Not got my laptop with the files at home, But some of the engine I have mapped/biult tend to run between 8 and 14dg ranging from 480ftlb and 550ftlb,
Rods last engine ran 18dg Ign at 2.5bar boost,
I have found so far that running a Cossie down to 8dg does not cause any real rise in EGT the only problem I find is when the intake temp goes in to ign retard you tend to loose lost more power than a large ign angle low comp engine, So the secret is no high temps and my installs dont suffer from this
.Mark
awesome post mark.
passionford at its best when tuners are prepared to put some details to what they are doing like that.
im amazed you have found single figure advance not rising the egts just by controlling the intake temps like that. certainly not most peoples experience.
shows the importance of the overall package
I am genuinely impressed by that. more so than rods engine in a lot of ways as working with some of the in built limitations of the YB is in many ways harder than just replacing everything to make it work imho
13-10-2007 | 07:26 AM
#103
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From: barry-south wales
generally we lower the compression when going for more power in a reliable form, we raise the compression when using new technology's, we havent yet fathomed out what these are yet, but as soon as we do, we'll get back to you
13-10-2007 | 12:46 PM
#105
Originally Posted by Chip-3Door
Your engine doesnt have this prolem becuase its a piece of shit asmatic single cam pushrod motor, 20psi on your motor is a less efficient cylinder fill than 10psi on most modern engines.
Consequently, you can get away with squeezing harder the half full cylinder you have! (in relative terms)
The easiest way for people to view this topic might be to think in terms of TORQUE PER LITRE as that is what is really the key thing here, and relative to a 500lbft cossie, your engine makes bugger all, in fact yours probably makes less torque per litre than a totally run of the mill stage 3 cossie
so your engine says NOTHING about what a 250lbft + litre engine would do, as it isnt one.
Dont get me wrong I really do LOVE the LS1 and LS2 series of engines, the genius of them is in the fact they are so amazingly simply, and yet still (despite their capacity) manage to cram massive horsepower into a very lightweight package, I think its an awesome choice for your car, and the results you are getting are nothing short of legendary, but you need to remember that you are doing so in a VERY low state of tune, your engine is teaching you nothing about big power outputs, because the reality is that until you start getting upto 1500bhp, you arent in the same league as a 500bhp cossie, and until you are at 1000bhp you arent even matching a stage 3 cossie.
Your exhaust gas temps at 400bhp are probably still cold enough to put back in again
when is it comes down to who is the fool the guy throwing money at a 40+year old engine ringing it to within an inch of its life not knowing WHEN its going to blow up, or the guy who buys a pretty newish motor spends very little on it and makes it do fook all work and gets the same if not better than most's result i know who the fool is.
13-10-2007 | 12:49 PM
#106
Originally Posted by Chip-3Door
Originally Posted by Mark Shead
Chip
Not got my laptop with the files at home, But some of the engine I have mapped/biult tend to run between 8 and 14dg ranging from 480ftlb and 550ftlb,
Rods last engine ran 18dg Ign at 2.5bar boost,
I have found so far that running a Cossie down to 8dg does not cause any real rise in EGT the only problem I find is when the intake temp goes in to ign retard you tend to loose lost more power than a large ign angle low comp engine, So the secret is no high temps and my installs dont suffer from this .
Mark
Not got my laptop with the files at home, But some of the engine I have mapped/biult tend to run between 8 and 14dg ranging from 480ftlb and 550ftlb,
Rods last engine ran 18dg Ign at 2.5bar boost,
I have found so far that running a Cossie down to 8dg does not cause any real rise in EGT the only problem I find is when the intake temp goes in to ign retard you tend to loose lost more power than a large ign angle low comp engine, So the secret is no high temps and my installs dont suffer from this
.Mark
im amazed you have found single figure advance not rising the egts just by controlling the intake temps like that. certainly not most peoples experience.
shows the importance of the overall package
I am genuinely impressed by that. more so than rods engine in a lot of ways as working with some of the in built limitations of the YB is in many ways harder than just replacing everything to make it work imho
theres a lot of theory written about internal combustion and its workings, but nothing beats having been out there and tried it first hand for the results rather than being told what SHOULD happen.
13-10-2007 | 01:39 PM
#107
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From: North EAST
Ok,the gist of this one says don't go for 9.1 comp.Then how comes Stians Escort runs 9.1 comp,a huge f/off T88 turbo at 3 bar to give 919 brake and does'nt melt.Is it only because of race fuel.
13-10-2007 | 01:57 PM
#108
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From: UK
Originally Posted by allsteel
Ok,the gist of this one says don't go for 9.1 comp.Then how comes Stians Escort runs 9.1 comp,a huge f/off T88 turbo at 3 bar to give 919 brake and does'nt melt.Is it only because of race fuel.
13-10-2007 | 06:11 PM
#109
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From: scotland
Originally Posted by allsteel
Ok,the gist of this one says don't go for 9.1 comp.Then how comes Stians Escort runs 9.1 comp,a huge f/off T88 turbo at 3 bar to give 919 brake and does'nt melt.Is it only because of race fuel.
16-10-2007 | 12:38 PM
#110
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From: Warsaw, Poland
Originally Posted by Chip-3Door
Gareth, I thought that the engine in my sierra automatically updates the shape of the cylinder head and bore to stroke ratio each year magically as new technology is uncovered, do you mean to tell me that in reality the lump of iron that is in it doesnt really morph power rangers style into an all aluminium evo engine with a modern design of cylinder head and a longer stroke than bore?
surely not?
surely not?
4G63 is actually iron block and aluminium head
and with rather low comp as well Runs I thnk even higher boost then Cossies in tuned versions (I mean standard internal tuned version, not custom builds, because as this thread proves they hardly compare). It's quite common to run one at 1.8-2.0 bar on standard turbo and everything expet exhaust.
16-10-2007 | 02:16 PM
#111
............
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From: West Mids
Originally Posted by Stavros
The BRM V16 engine was a 1950s supercharged 1.5litre F1 engine and ran 72psi, thats SEVENTY FUCKING TWO PSI BOOST, in 1951
.
Who was mentioning technological advances earlier?!!
16-10-2007 | 02:18 PM
#112
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From: West Mids
16-10-2007 | 02:42 PM
#114
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From: barry-south wales
Originally Posted by Benni
Can I ask what Compression is please? If it's majorly complicated just don't bother.
It is the ratio between the volume of the cylinder, when the piston is at the bottom of its stroke, and the volume when the piston is at the top of its stroke
16-10-2007 | 02:45 PM
#116
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From: You cant have pie without coolWhip
MattRS1600i
He also stated that at Albi 1953, Fangio's V16 had a claimed 72 psi boost ( stavros made this up ) (4.9 ata) and 585 bhp @ 11,800 rpm. He reached 186 mph.
16-10-2007 | 04:24 PM
#120
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From: North Korea
I think youl find it says...
What did it originally say?
I got the 72psi thing from a book, as anyone can write any old shit on Wikipedia, as we have proven
He also stated that at Albi 1953, Fangio's V16 had a claimed 72 psi boost ( Matt RS1600i bums men ) (4.9 ata) and 585 bhp @ 11,800 rpm. He reached 186 mph.
What did it originally say?
I got the 72psi thing from a book, as anyone can write any old shit on Wikipedia, as we have proven