improving cylinder squish
Discussion
Hello peeps. looking for some tech advice on my toyota 4efte engine.
I'm currently converting the 4efe engine over to the turbo engine found in the starlet. the turbo i have choosen is the garrett T2. off the rs fiesta.
The engine has been stripped down and I av had all bores over sized and purchased wasco piston 8:1 ratio, and rods which i av fitted. along with the turbo head gasket. the question is this should i improve the cylinder squish. I have measured all 4 cylinders for thr squish and all r different (with head assem) cyl 1= 0.045in, cly 2= 0.048in, cly 3= 0.046in, cly4 = 0.042inc. It is for road and track. and the car will be fitted with a wet noss system at a later date.
I'm currently converting the 4efe engine over to the turbo engine found in the starlet. the turbo i have choosen is the garrett T2. off the rs fiesta.
The engine has been stripped down and I av had all bores over sized and purchased wasco piston 8:1 ratio, and rods which i av fitted. along with the turbo head gasket. the question is this should i improve the cylinder squish. I have measured all 4 cylinders for thr squish and all r different (with head assem) cyl 1= 0.045in, cly 2= 0.048in, cly 3= 0.046in, cly4 = 0.042inc. It is for road and track. and the car will be fitted with a wet noss system at a later date.
i have doubled up head gaskets before on this motor running the old piston and rod configeration with the garrett turbo. the head gaskets wen fitted measured 0.030in each, and deck to piston clearance was around 0.009in in all cylinders (some high some lower. The main problem i found was it was good on hard acceleration my wide band lamber sensor reading slightly rich, but at steady throttle the mixture read rich. not gettin good scavaging in the cylinders i think + the exaust gas temp shoots up.
When you measured the squish did you take several measurements from each cylinder to compensate for piston rock? Those figures you have are fine so personally I wouldn't bother skimming the deck or any of the pistons. It's important to have squish but go to tight and you may have issues. No squish means a less efficient engine. Two head gaskets is a crap idea, twice as likely to leak and less squish. Definately not an engineering solution.
the 2 head gaskets was purly for experimental reasons to get an idea of wat would happen with increased squish on this engine by monterin the combustion process by way of reading individual exhaust gasses HC,O2,CO2,CO,NOX and temp. and i'm a completely compatant engine tunner thanks.
The way i see things r competition engines do not require low speed combustion quality and cruise economy. what we aim for is the best hp over a range of about 35-45% engine revs at the top of the power band, wen throttle opening wider than 60%. these circumstances lead to mixture density bein quite high, so there is a corresponding increase in mixture turbulenceas as the piston rises to TDC on the compression stroke. so wat i'm gettin at is increasing squish clearance on race engines sounds good. This I have found out for my self and have seen proven power gains. On the other hand wen i have delt with normally asperated high compression ratio engine thy av a squish of around 0.035in. reducing the risk of detonation by increasin Turbulence benafiting fuel economy, preventing stale gas pockets from forming and enhances heat transfer at the spark initiated flame front.
The way i see things r competition engines do not require low speed combustion quality and cruise economy. what we aim for is the best hp over a range of about 35-45% engine revs at the top of the power band, wen throttle opening wider than 60%. these circumstances lead to mixture density bein quite high, so there is a corresponding increase in mixture turbulenceas as the piston rises to TDC on the compression stroke. so wat i'm gettin at is increasing squish clearance on race engines sounds good. This I have found out for my self and have seen proven power gains. On the other hand wen i have delt with normally asperated high compression ratio engine thy av a squish of around 0.035in. reducing the risk of detonation by increasin Turbulence benafiting fuel economy, preventing stale gas pockets from forming and enhances heat transfer at the spark initiated flame front.
Edited by nastyrash2003 on Tuesday 13th October 02:58
stevieturbo said:
Then why are you also using a crap ancient T2 ? Why not use something modern ?
Most of the old T-series are laggy and make little power. Very innefficient compared to more modern units. Again, that will be a hell of a lot more important than squish.
Agree with this.Most of the old T-series are laggy and make little power. Very innefficient compared to more modern units. Again, that will be a hell of a lot more important than squish.
You could fit something like a GT2554R, would seem to be a good balance between spool and power on a 4E.
OP, if you're only racing at higher rpm's and focused on low compression and turbulence then you hardly need squish at all. Anything under .060" will help but as said you'll have masses of turbulance. You may have to run accept the engine runs an octane point lower and det would be more likely but you may be able to get around that. Imo the trade off is a balancing act between squish or a bigger chamber volume for more fuel air. Personally I lean towards squish/quench if the mechanicals allow it.
lol!. I'm using this turbo simply because it was the smallest 2 hand and did not give high boost presure for my stock engine. I was hoping to get some good advice on squish 2 help combat the lagggg and even if possible increase compresion ratio from 8.2. i have recently read a artical on the sprintex charger, and am well impressed, thinking this would more suit my road-track needs. still squish info i still requir. and maybe u can sugest a better small modert turbo best to fill my needs.
nastyrash2003 said:
lol!. I'm using this turbo simply because it was the smallest 2 hand and did not give high boost presure for my stock engine. I was hoping to get some good advice on squish 2 help combat the lagggg and even if possible increase compresion ratio from 8.2. i have recently read a artical on the sprintex charger, and am well impressed, thinking this would more suit my road-track needs. still squish info i still requir. and maybe u can sugest a better small modert turbo best to fill my needs.
smallest second hand ?wastegate controls boost pressure, not the turbo Unless of course the turbo is incapable of supplying the engine.
Smallest second hand unit that works well...oddly enough would be the standard CT9 off a starlet turbo !! Isnt that kind of obvious ??
Lag is f
k all to do with squish...its down to poor CR choice, and crap tubo choice !Marf said:
stevieturbo said:
Then why are you also using a crap ancient T2 ? Why not use something modern ?
Most of the old T-series are laggy and make little power. Very innefficient compared to more modern units. Again, that will be a hell of a lot more important than squish.
Agree with this.Most of the old T-series are laggy and make little power. Very innefficient compared to more modern units. Again, that will be a hell of a lot more important than squish.
You could fit something like a GT2554R, would seem to be a good balance between spool and power on a 4E.
stevieturbo said:
nastyrash2003 said:
lol!. I'm using this turbo simply because it was the smallest 2 hand and did not give high boost presure for my stock engine. I was hoping to get some good advice on squish 2 help combat the lagggg and even if possible increase compresion ratio from 8.2. i have recently read a artical on the sprintex charger, and am well impressed, thinking this would more suit my road-track needs. still squish info i still requir. and maybe u can sugest a better small modert turbo best to fill my needs.
smallest second hand ?wastegate controls boost pressure, not the turbo Unless of course the turbo is incapable of supplying the engine.
Smallest second hand unit that works well...oddly enough would be the standard CT9 off a starlet turbo !! Isnt that kind of obvious ??
Lag is f
k all to do with squish...its down to poor CR choice, and crap tubo choice !Edited by nastyrash2003 on Tuesday 13th October 10:23
Boosted LS1 said:
OP, if you're only racing at higher rpm's and focused on low compression and turbulence then you hardly need squish at all. Anything under .060" will help but as said you'll have masses of turbulance. You may have to run accept the engine runs an octane point lower and det would be more likely but you may be able to get around that. Imo the trade off is a balancing act between squish or a bigger chamber volume for more fuel air. Personally I lean towards squish/quench if the mechanicals allow it.
this is more like it, now we r talkin. wat would u recomend squish clearence for wat i want from the engine= road-track use. want to increase squish but am worried about the effects of forced induction and noss if i go to low. would not want the engine to become solid.nastyrash2003 said:
i'm just tryin to aid engine proformance out of the boost range as well as keep cruise. and i wrote " to hand" not second hand!.
I thought you said you were purely looking at it from a race perspective and above 60% throttle openings, so off boost and low revs wasn't an issue?In my opinion on the size and level of tune of the engine and turbo you appear to be talking about I would be much more interested in making sure you have a good exhaust manifold (if you are using a crap cast oe one) and that the head flows effectively rather than concentrating on squish amongst other things. Surely you will get much larger gains from making the basics right first?
I have always found that a good tubular manifold, downpipe and exhaust system make a massive difference on smaller turbo cars that come with factory fit stuff. In my 205's engine (2.0 8V turbo) the cast manifold and exhaust housing of the turbo are the main restrictions and you can see 200+bhp from a otherwise 150bhp engine on near enough the same boost just from swapping these for better flowing items!
bales said:
nastyrash2003 said:
i'm just tryin to aid engine proformance out of the boost range as well as keep cruise. and i wrote " to hand" not second hand!.
I thought you said you were purely looking at it from a race perspective and above 60% throttle openings, so off boost and low revs wasn't an issue?In my opinion on the size and level of tune of the engine and turbo you appear to be talking about I would be much more interested in making sure you have a good exhaust manifold (if you are using a crap cast oe one) and that the head flows effectively rather than concentrating on squish amongst other things. Surely you will get much larger gains from making the basics right first?
I have always found that a good tubular manifold, downpipe and exhaust system make a massive difference on smaller turbo cars that come with factory fit stuff. In my 205's engine (2.0 8V turbo) the cast manifold and exhaust housing of the turbo are the main restrictions and you can see 200+bhp from a otherwise 150bhp engine on near enough the same boost just from swapping these for better flowing items!
I was just explainin y i put the 2 stok head gaskets together, experimenting with the cylinder squish. thw taking it above the 0.060in that has just bin recomenden. was no good on steady throttle postion, cruise economy went out the window with masive amounts of HC and o2 levels in exhaust gasses. but yet improvments in throttle respons and power.
Edited by nastyrash2003 on Tuesday 13th October 11:27
Edited by nastyrash2003 on Tuesday 13th October 11:40
nastyrash2003 said:
bales said:
nastyrash2003 said:
i'm just tryin to aid engine proformance out of the boost range as well as keep cruise. and i wrote " to hand" not second hand!.
I thought you said you were purely looking at it from a race perspective and above 60% throttle openings, so off boost and low revs wasn't an issue?In my opinion on the size and level of tune of the engine and turbo you appear to be talking about I would be much more interested in making sure you have a good exhaust manifold (if you are using a crap cast oe one) and that the head flows effectively rather than concentrating on squish amongst other things. Surely you will get much larger gains from making the basics right first?
I have always found that a good tubular manifold, downpipe and exhaust system make a massive difference on smaller turbo cars that come with factory fit stuff. In my 205's engine (2.0 8V turbo) the cast manifold and exhaust housing of the turbo are the main restrictions and you can see 200+bhp from a otherwise 150bhp engine on near enough the same boost just from swapping these for better flowing items!
Without sounding rude..which it will. It slounds like you dont know what you are doing.
What vehicle is this in ?
Some modern turbos like a GT17 or GT22 or similar will spool well, and make reasonable power.
How much power do you hope to achieve ? and what sort of power delivery do you need ? rpm band ?
What vehicle is this in ?
Some modern turbos like a GT17 or GT22 or similar will spool well, and make reasonable power.
How much power do you hope to achieve ? and what sort of power delivery do you need ? rpm band ?
can do but want it for road use aswell. will be modding the inlet valve head by 30degree back cutting + a 0.035in undercut valve stem thn polished cut area. thn inlet bowl and throat polishing (takin all thm edges away). + hopping on modding the throttle body, taking the throttle plate up to 50mm (might be a bit big will find out).
[quote=stevieturbo]Without sounding rude..which it will. It slounds like you dont know what you are doing.
What vehicle is this in ?
Some modern turbos like a GT17 or GT22 or similar will spool well, and make reasonable power.
How much power do you hope to achieve ? and what sort of power delivery do you need ? rpm band ?[/quo
OH! Ok thanks for ur prognosis, if i want turbo info i will be sure 2 contact u. and on a serious note thanks for the turbo model numbers as most of my work is on n/a engines and have fallen a bit behind in turbo tech. bin reaserching electronic boost modulation controlers (impresive stuff). can u recomend 1.
What vehicle is this in ?
Some modern turbos like a GT17 or GT22 or similar will spool well, and make reasonable power.
How much power do you hope to achieve ? and what sort of power delivery do you need ? rpm band ?[/quo
OH! Ok thanks for ur prognosis, if i want turbo info i will be sure 2 contact u. and on a serious note thanks for the turbo model numbers as most of my work is on n/a engines and have fallen a bit behind in turbo tech. bin reaserching electronic boost modulation controlers (impresive stuff). can u recomend 1.
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