About to buy engine internals - some questions
03-21-2012, 05:49 AM
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About to buy engine internals - some questions
Searched the ---- out of here and google multiple times, but still a few items that I can't make a final decision on - looking for any advice or thoughts! Engine is torn about, going to order everything very very soon.
I'll first lay out general plan/goal.
99 BP4W
GT2871 .86 A/R
350whp goal (20-24psi)
93 octane (currently have WI kit on car, but I want to remove it, not have to rely on it)
Not DD, but not track only. Street driven most of the time, but able to handle track days, autox, spirited driving.
Supertech pistons
Eagle rods
ARP head/main studs
BE oil pump
etc, etc.... basically what TSE does for theirs
1. Bearings. ACL race is the standard answer for MT. My builder's concern with them is they are super hard (good for race motor), which makes them much more likely to wear faster from scoring, etc.... Google search brings this up some too. Solution might be to change oil super frequent, etc...but maybe not the best option for mainly street car?
Is there some sort of good middle ground here? I looked into Clevite and King, but it seems they only make "aluminum" or "OEM replacement" bearings- I've also seen some failed Kings ones from FM built motors (bbundy). Clevite Trimetal series is what my builder mentioned as a good compromise, but yeah, seems like they do not make them for Miata.
ACL makes both the Duraglide and Aluglide for Miata... I'm thinking these may be the best for me---- THOUGHTS??
2. Pistons. Some good threads on here regarding compression ratio (one from like 2008). 8.6 are the preferred setup for track- low heat, most safe, etc. I was thinking 9.0 as a good compromise. I'm also planning on trying out "exhintake" intake cam swap to get a good bit more lift and duration for pretty cheap. I've been reading into dynamic compression and how cams/valve timing affect all that, and end result is I lose about 0.5 CR with the exhintake.....is my thinking of considering 9.5 static CR pistons for this build sane? 9:1 CR, stock cams DCR should be = 9.5 CR exhintake cam DCR. EDIT: or should I just see the loss of DCR as a "gain" for even lower effective compression ratio and go with 8.6?
Overthinking this all to some degree I know, just trying to make the best decision based on my current goals.
Thanks in advance!
I'll first lay out general plan/goal.
99 BP4W
GT2871 .86 A/R
350whp goal (20-24psi)
93 octane (currently have WI kit on car, but I want to remove it, not have to rely on it)
Not DD, but not track only. Street driven most of the time, but able to handle track days, autox, spirited driving.
Supertech pistons
Eagle rods
ARP head/main studs
BE oil pump
etc, etc.... basically what TSE does for theirs
1. Bearings. ACL race is the standard answer for MT. My builder's concern with them is they are super hard (good for race motor), which makes them much more likely to wear faster from scoring, etc.... Google search brings this up some too. Solution might be to change oil super frequent, etc...but maybe not the best option for mainly street car?
Is there some sort of good middle ground here? I looked into Clevite and King, but it seems they only make "aluminum" or "OEM replacement" bearings- I've also seen some failed Kings ones from FM built motors (bbundy). Clevite Trimetal series is what my builder mentioned as a good compromise, but yeah, seems like they do not make them for Miata.
ACL makes both the Duraglide and Aluglide for Miata... I'm thinking these may be the best for me---- THOUGHTS??
2. Pistons. Some good threads on here regarding compression ratio (one from like 2008). 8.6 are the preferred setup for track- low heat, most safe, etc. I was thinking 9.0 as a good compromise. I'm also planning on trying out "exhintake" intake cam swap to get a good bit more lift and duration for pretty cheap. I've been reading into dynamic compression and how cams/valve timing affect all that, and end result is I lose about 0.5 CR with the exhintake.....is my thinking of considering 9.5 static CR pistons for this build sane? 9:1 CR, stock cams DCR should be = 9.5 CR exhintake cam DCR. EDIT: or should I just see the loss of DCR as a "gain" for even lower effective compression ratio and go with 8.6?
Overthinking this all to some degree I know, just trying to make the best decision based on my current goals.
Thanks in advance!
Last edited by aaronc7; 03-21-2012 at 06:19 AM.
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03-21-2012, 06:54 PM
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I guess to be a bit more concise on the questions I have:
Has anyone used the ACL Duraglide series? Thoughts, impressions?
My gut feeling for the pistons is to just run 8.6, lowest I can go for biggest safety margin and ease of tuning (doing it myself). I just don't want to hit MBT and still be far from possible knock region and "giving up power". Maybe 350whp on 93 octane and hitting MBT is not remotely possible-- im not sure. I have WI on the car now, but I do not want to rely on that... failsafes will be a pain in the ***, and most applications of WI are just not very precise at all IMO.
Has anyone used the ACL Duraglide series? Thoughts, impressions?
My gut feeling for the pistons is to just run 8.6, lowest I can go for biggest safety margin and ease of tuning (doing it myself). I just don't want to hit MBT and still be far from possible knock region and "giving up power". Maybe 350whp on 93 octane and hitting MBT is not remotely possible-- im not sure. I have WI on the car now, but I do not want to rely on that... failsafes will be a pain in the ***, and most applications of WI are just not very precise at all IMO.
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03-22-2012, 04:03 AM
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Here's a pretty good sum up of what options we have... at least that I have found.
King: http://www.kingbearings.com/oem_replacement.php
OEM replacement, Alecular Alloy (AM), an alloy of aluminum, tin and copper-Plus Alloy on high-strength steel. (Bi-metal bearing). Designed for low and moderate loads.
Clevite: http://www.mahle-aftermarket.com/C12...NFSRF794STULEN
For OEM engines, looks like an aluminum and silicon bimetal bearing, not as detailed info on the page there, but I didn't dig super deep into those.
ACL Aluglide: http://www.aclus.com/engine_bearings.htm
Bottom of the page it talks about replacing some of the Duraglide bearings with Aluglide- I think this is the case for the Miata. I found the part number for us, and googled it and got results for both Duraglide and Aluglide. Probably hard to find Duraglide these days. Aluglide is aluminum and silicone bimetal
ACL Duraglide: is traditional trimetal bearing, which support a greater load for extended periods of time. The Clevite link provides good info on trimetal details.
ACL Race: http://www.aclperformance.com.au/us/...bearingsus.htm
Seems to be the ONLY trimetal for our B6s and BPs that I have found.
My concern with it was too extreme or hard for reasonable street use, but on ACL page it mentions it's use as "street, moderate track", so I think I am just going to with them.
I've found/heard of a few King/Clevite failures on the miata forums, but they only seemed to be on dedicated track car type application...normal street car, probably be just fine running them. But for those who want to dig way too deep into a subject like me..hope this info helps out.
Bottom line to me it looks like ACL Race for track car or relatively high power/occasionally tracked car. More moderate builds that are also DD, clevite or acl aluglide look good. King seem the most meh and the fact they even state designed for low and moderate loads would kinda scare me away for a forged engine build.
King: http://www.kingbearings.com/oem_replacement.php
OEM replacement, Alecular Alloy (AM), an alloy of aluminum, tin and copper-Plus Alloy on high-strength steel. (Bi-metal bearing). Designed for low and moderate loads.
Clevite: http://www.mahle-aftermarket.com/C12...NFSRF794STULEN
For OEM engines, looks like an aluminum and silicon bimetal bearing, not as detailed info on the page there, but I didn't dig super deep into those.
ACL Aluglide: http://www.aclus.com/engine_bearings.htm
Bottom of the page it talks about replacing some of the Duraglide bearings with Aluglide- I think this is the case for the Miata. I found the part number for us, and googled it and got results for both Duraglide and Aluglide. Probably hard to find Duraglide these days. Aluglide is aluminum and silicone bimetal
ACL Duraglide: is traditional trimetal bearing, which support a greater load for extended periods of time. The Clevite link provides good info on trimetal details.
ACL Race: http://www.aclperformance.com.au/us/...bearingsus.htm
Seems to be the ONLY trimetal for our B6s and BPs that I have found.
My concern with it was too extreme or hard for reasonable street use, but on ACL page it mentions it's use as "street, moderate track", so I think I am just going to with them.
I've found/heard of a few King/Clevite failures on the miata forums, but they only seemed to be on dedicated track car type application...normal street car, probably be just fine running them. But for those who want to dig way too deep into a subject like me..hope this info helps out.
Bottom line to me it looks like ACL Race for track car or relatively high power/occasionally tracked car. More moderate builds that are also DD, clevite or acl aluglide look good. King seem the most meh and the fact they even state designed for low and moderate loads would kinda scare me away for a forged engine build.
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