7m bottom end capability.

Joe123

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#1
Hi guys I'm new to this forum and I need a few opinions from you guys. My 7m has about 180,000 miles on it but about 1,000 miles ago I rebuilt the top end due to a hg failure and replaced the old stock one with a metal one with arps tq to 90ft/lb. I'm planning to do the Lexus afm/550s mod, just bought a mk4 tt fuel pump, lipp afm, afpr kit, rc 550s with plug and play wiring adapters. Already have a 57 trim ct26 on here. So my question is would the stoke bottom end with al those miles be able to handle about 400rwhp? Or more? The car used to be my dads and he maintained it well regularly and said he babies it a lot.
 

Nick M

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#2
It isn't so much that power but how you treat it. Engines 101, the rods are the first to go.
 

Joe123

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#3
I don't abuse it by any means . I never take the car to its limits, I don't remember ever even revving past 5.5k. So do you think it would be okay to have 18lbs of boost on a bottom end with that many miles?
 

Joe123

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#4
Can someone please put in their input, I don't wana mess this up and have to take the whole entire engine apart due to a broken rod
 

Janch

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#5
if engine is in good shape and maintained well, then with supporting mods stock internals will hold well over 400whp. in other forums ppl say they've been pushing 500rwhp with stock internals for years. But ive heard 500whp is the limit so safe zone would be 450whp so i think you should be safe with your goal.
 

Joe123

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#6
Alright thank you. I was just nervous that the old bottom end wouldn't handle that power. According to previous owners it was well maintenances and babied. Thank you
 

1-2clutch-u

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#7
id say pistons are the first to go by most peoples fails. Its mostly melted pistons and or broken ring lands. I could be wrong but you will be fine if tuned right and good gas.
 

Nick M

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#8
So do you think it would be okay to have 18lbs of boost on a bottom end with that many miles?
The owners manual (which is never read) correctly states that repeated boost pressures above 8 psi will cause serious engine damage. Continuous being the key word.
 

Janch

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#10
Yeah also owner manual says to torque Head gasket at 58ft lbs.. and does 35psi fits in "above 8 psi will cause serious engine damage" statement?... joking.

Make sure to tune correctly and you should have no problems with melting pistons at your power goal.
 

Nick M

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#11
id say pistons are the first to go by most peoples fails. Its .
Well, you would be wrong. Pistons are lost due to severe detonation, and that assumes the combustion chamber has a nearly unbreakable seal. Something you don't want.
 

VanSupra

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#13
Do a compression and leak down test which will show any weakness's if any, to give you some peace of mind in regards to the health of your engine.
 

suprarx7nut

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#14
If you're going to do the lex/550 mod you need some tuning if you want it to be reliable (stock bottom end or not). Don't worry so much about the internals - they've proven capable beyond your power goal. The key is tuning. A poor tune at stock boost levels (caused by a boost leak, removal of EGR system while still running US ECU, timing advanced too far, etc...) can kill a motor. A good tune can yield safe power nearly as high as you dare go.

You need tuning, that's my point.

As an aside: If you're goal is 400 whp I hope you plan on abusing it a little. What's the point if not? If you're going to build it up (which you should because these are a blast to drive when modified) you should plan on abusing it and plan on having to rebuild it at some point. Go in with the assumption that it's going to have some problems and it's going to require a lot of work. If you expect it to all go smoothly and make 400whp without any hiccups you're probably in for a painful mk3 owning experience. That's my 0.02.

Enjoy!
 

Grandavi

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#15
Im running a stock'ish bottom end with MHG and stock head. Standalone system with a T4 6262 turbo and 1000 cc injectors. 385-400 rwhp at the wheels at about 14 psi boost. The engine seems to handle this level well, but to go higher would be difficult for me as I only have 91 octane pump here and I am not really thrilled about running unleaded VP109 octane race fuel for how I drive.. lol.

The bottom line is (reality-wise) increase power = decreased reliability. On a stock ECU system, you will always run pig-rich and a CT26 is limited in it's flow. With a BPU setup (as you are talking about) as long as your bottom end is still solid, you shouldn't have any issues past the part where power reduces reliability.

Wideband, Exhaust gas temp gauge are the two first gauges I would get. The EGT gauge was a bit of an eye-opener for me because I never realised how the turbo actually performs better as the heat climbs, but long boost pulls can make the heat climb fairly high on my setup, so I limit my highway running speed now for long distance.

Remember that 400 rwhp is more like 500'ish at the crank.
 

aljordan

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#16
The lexus afm / 550 cc mod is essentially a scaled up version of the stock afm, and stock 440 injectors. The car will run *flawlessly* with the larger lexus afm housing and 550 injectors. It's a near perfect upgrade to allow more boost while still maintaining Toyota reliability. Absolutley zero tuning is required for this modification.

http://suprasonic.org/public_html/lexusriemer/lexusnotes.html