Gen 4 5.3 flat top pistons and boost ?’s
Thread Starter
On The Tree
Joined: Sep 2014
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Gen 4 5.3 flat top pistons and boost ?’s Hi I have a 5.3 that I am building for boost and was curious as to which heads to run with a flat top piston 5.3? This engine is going in a 93 Mazda rx7 which is decently light. Anyways what would you guys do to prep then engine? The engine still shows its cross hatch pattern in bores very well. Also I bought engine with no cam and heads so buying all that stuff.
Thanks
Richard
Thanks
Richard
If its a high mileage short block and was pulled without issue then I'd run it.
If the engine is already apart, gap the piston rings and new bearings if you feel inclined or reuse the old ones if they look good.
Cam will depend on the turbo you select and budget.
Fuel type would determine which head I'd run, E85 and 243's or pump gas and 317's.
This is my personal preference and others will feel differently and you should certainly take their info into consideration as well as some guys on here have built way more of these engines than me.
Lotta guys run 243 heads on the 5.3 with boost, I myself have a set of CNC ported 317's I'll be using with flat tops should bring the static compression ratio in right around 9.5:1.
Either head will work well but the 243 will have higher compression for faster lighting but also smaller tuning error window.
If the engine is already apart, gap the piston rings and new bearings if you feel inclined or reuse the old ones if they look good.
Cam will depend on the turbo you select and budget.
Fuel type would determine which head I'd run, E85 and 243's or pump gas and 317's.
This is my personal preference and others will feel differently and you should certainly take their info into consideration as well as some guys on here have built way more of these engines than me.
Lotta guys run 243 heads on the 5.3 with boost, I myself have a set of CNC ported 317's I'll be using with flat tops should bring the static compression ratio in right around 9.5:1.
Either head will work well but the 243 will have higher compression for faster lighting but also smaller tuning error window.
Thread Starter
On The Tree
Joined: Sep 2014
Posts: 129
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If its a high mileage short block and was pulled without issue then I'd run it.
If the engine is already apart, gap the piston rings and new bearings if you feel inclined or reuse the old ones if they look good.
Cam will depend on the turbo you select and budget.
Fuel type would determine which head I'd run, E85 and 243's or pump gas and 317's.
This is my personal preference and others will feel differently and you should certainly take their info into consideration as well as some guys on here have built way more of these engines than me.
Lotta guys run 243 heads on the 5.3 with boost, I myself have a set of CNC ported 317's I'll be using with flat tops should bring the static compression ratio in right around 9.5:1.
Either head will work well but the 243 will have higher compression for faster lighting but also smaller tuning error window.
If the engine is already apart, gap the piston rings and new bearings if you feel inclined or reuse the old ones if they look good.
Cam will depend on the turbo you select and budget.
Fuel type would determine which head I'd run, E85 and 243's or pump gas and 317's.
This is my personal preference and others will feel differently and you should certainly take their info into consideration as well as some guys on here have built way more of these engines than me.
Lotta guys run 243 heads on the 5.3 with boost, I myself have a set of CNC ported 317's I'll be using with flat tops should bring the static compression ratio in right around 9.5:1.
Either head will work well but the 243 will have higher compression for faster lighting but also smaller tuning error window.
I wanna say 10.5:1 which you can totally do on pump gas, you just have to be a little more cautious with the tune.
If you're having a professional tuner do the work then you'd be fine.
I'm only speaking from the realm that all pump gas is not created equal and if you drive your car everywhere like I do then i like to be a little conservative to compensate for crappy gas.
Its probably pretty negligible but I like to air on the side of caution.
If you're having a professional tuner do the work then you'd be fine.
I'm only speaking from the realm that all pump gas is not created equal and if you drive your car everywhere like I do then i like to be a little conservative to compensate for crappy gas.
Its probably pretty negligible but I like to air on the side of caution.
Thread Starter
On The Tree
Joined: Sep 2014
Posts: 129
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I wanna say 10.5:1 which you can totally do on pump gas, you just have to be a little more cautious with the tune.
If you're having a professional tuner do the work then you'd be fine.
I'm only speaking from the realm that all pump gas is not created equal and if you drive your car everywhere like I do then i like to be a little conservative to compensate for crappy gas.
Its probably pretty negligible but I like to air on the side of caution.
If you're having a professional tuner do the work then you'd be fine.
I'm only speaking from the realm that all pump gas is not created equal and if you drive your car everywhere like I do then i like to be a little conservative to compensate for crappy gas.
Its probably pretty negligible but I like to air on the side of caution.
I'd keep an eye out on this forum for a used cam as well, something like a BMR/LJMS Stage 2 Turbo cam (they're the same) or a Tick 5.3 Stage 2 Turbo cam.
Either of these will work very well with a range of turbos from 7875 up to the larger S475 turbos, the cam will really determine much power the engine will make efficiently.
You've gotta be quick in picking them up because they go fast.
Thread Starter
On The Tree
Joined: Sep 2014
Posts: 129
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Sounds like a good deal with rockers, you'd certainly pay more for 243's as they are far more popular.
I'd keep an eye out on this forum for a used cam as well, something like a BMR/LJMS Stage 2 Turbo cam (they're the same) or a Tick 5.3 Stage 2 Turbo cam.
Either of these will work very well with a range of turbos from 7875 up to the larger S475 turbos, the cam will really determine much power the engine will make efficiently.
You've gotta be quick in picking them up because they go fast.
I'd keep an eye out on this forum for a used cam as well, something like a BMR/LJMS Stage 2 Turbo cam (they're the same) or a Tick 5.3 Stage 2 Turbo cam.
Either of these will work very well with a range of turbos from 7875 up to the larger S475 turbos, the cam will really determine much power the engine will make efficiently.
You've gotta be quick in picking them up because they go fast.
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TECH Fanatic
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Hi I have a 5.3 that I am building for boost and was curious as to which heads to run with a flat top piston 5.3? This engine is going in a 93 Mazda rx7 which is decently light. Anyways what would you guys do to prep then engine? The engine still shows its cross hatch pattern in bores very well. Also I bought engine with no cam and heads so buying all that stuff.
Thanks
Richard
Thanks
Richard
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Verdad Gallardo The 5.3 I'm doing had 164,000 miles on it and still had cross hatches and good ring tension so my builder said I can definitely re use them which I will.
A lot plays into turbo sizing, intended use, power goal, space, transmission type, etc.
I think an S475 fits many applications from auto to manual trans and if you find a cheap used one can be a great place to start and make decent power.
5.3 w/ 317 heads, BTR or LJMS Stage 2 turbo cam, S475 outta be a safe 600whp car on pump gas and with used parts cheap too.
Thread Starter
On The Tree
Joined: Sep 2014
Posts: 129
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. Pump gas 93 octane, looking for 620-650hp
just curious why would replacing rings be iffy? I would run a quick brush hone down cylinders so new ring bed in properly.
Re-ringing is an iffy call, if the rings have tension and look to be in good shape then I'd reuse them.
The 5.3 I'm doing had 164,000 miles on it and still had cross hatches and good ring tension so my builder said I can definitely re use them which I will.
A lot plays into turbo sizing, intended use, power goal, space, transmission type, etc.
I think an S475 fits many applications from auto to manual trans and if you find a cheap used one can be a great place to start and make decent power.
5.3 w/ 317 heads, BTR or LJMS Stage 2 turbo cam, S475 outta be a safe 600whp car on pump gas and with used parts cheap too.
The 5.3 I'm doing had 164,000 miles on it and still had cross hatches and good ring tension so my builder said I can definitely re use them which I will.
A lot plays into turbo sizing, intended use, power goal, space, transmission type, etc.
I think an S475 fits many applications from auto to manual trans and if you find a cheap used one can be a great place to start and make decent power.
5.3 w/ 317 heads, BTR or LJMS Stage 2 turbo cam, S475 outta be a safe 600whp car on pump gas and with used parts cheap too.
If i dont know anything about the engine I am using (which is almost 100% of the time) I pull
it down and replace rings, bearings, and yes, cam bearings. We are talking about $200 in
parts. I am lazy, pulling an engine after it is in and running isnt high on my list, lol. Even if just
pulled it down for inspection, you need to replace some gaskets, bolts, so I dont ad them in
to the costs. Your results may very.
it down and replace rings, bearings, and yes, cam bearings. We are talking about $200 in
parts. I am lazy, pulling an engine after it is in and running isnt high on my list, lol. Even if just
pulled it down for inspection, you need to replace some gaskets, bolts, so I dont ad them in
to the costs. Your results may very.
Thread Starter
On The Tree
Joined: Sep 2014
Posts: 129
Likes: 0
If i dont know anything about the engine I am using (which is almost 100% of the time) I pull
it down and replace rings, bearings, and yes, cam bearings. We are talking about $200 in
parts. I am lazy, pulling an engine after it is in and running isnt high on my list, lol. Even if just
pulled it down for inspection, you need to replace some gaskets, bolts, so I dont ad them in
to the costs. Your results may very.
it down and replace rings, bearings, and yes, cam bearings. We are talking about $200 in
parts. I am lazy, pulling an engine after it is in and running isnt high on my list, lol. Even if just
pulled it down for inspection, you need to replace some gaskets, bolts, so I dont ad them in
to the costs. Your results may very.
If i dont know anything about the engine I am using (which is almost 100% of the time) I pull
it down and replace rings, bearings, and yes, cam bearings. We are talking about $200 in
parts. I am lazy, pulling an engine after it is in and running isnt high on my list, lol. Even if just
pulled it down for inspection, you need to replace some gaskets, bolts, so I dont ad them in
to the costs. Your results may very.
it down and replace rings, bearings, and yes, cam bearings. We are talking about $200 in
parts. I am lazy, pulling an engine after it is in and running isnt high on my list, lol. Even if just
pulled it down for inspection, you need to replace some gaskets, bolts, so I dont ad them in
to the costs. Your results may very.
TECH Fanatic
Joined: Feb 2015
Posts: 1,080
Likes: 178
93 octane I would target 9.5 or lower. Are you thinking 650whp or fwp?
If bearings look good, I wouldn't mess with them unless you have a bore gauge and mic to know where the current bearing tolerances are at. It seems many guys end up with bearing failures due to tight tolerances for the HP their running (crank flex causing failures). Factory rings and bearings seem to perform well so be cautious about replacing them with a lesser quality and poor results.
If bearings look good, I wouldn't mess with them unless you have a bore gauge and mic to know where the current bearing tolerances are at. It seems many guys end up with bearing failures due to tight tolerances for the HP their running (crank flex causing failures). Factory rings and bearings seem to perform well so be cautious about replacing them with a lesser quality and poor results.
I think all of the answers to your questions depend a lot on why somebody was selling you an engine with no cam or heads. This sounds suspicious to me. Why would you pull the cam and heads off a stock 5.3, then sell the shortblock? There are legit reasons, I guess, but I can think of a lot of bad ones.
I think all of the answers to your questions depend a lot on why somebody was selling you an engine with no cam or heads. This sounds suspicious to me. Why would you pull the cam and heads off a stock 5.3, then sell the shortblock? There are legit reasons, I guess, but I can think of a lot of bad ones.
Didn't hurt the block luckily so perhaps the op had a similar situation.
Been considering one myself but there as many to choose from as there are horror stories about issues.
I've used a BMS WMI kit with -20*F WWF and have added a bottle of HEET to it. Used the factory WWF tank and mounted everything under the hood for a compact install. The Devils own kit seems to be the cheapest with some nice stuff. I wouldn't want all the bells and whistles of a progressive,etc. A simple boost switch. Tune without it and then add it on top.