How much can a se bottom end handle ????

[SE10S]

I just bought a mx5 se and been looking in to getting a bit power out of it and just wondering whats the most it can handle before i need a built bottom end
thanks in advance

[Novice1]

I will be interested in replies to this topic.
Not owning an SE but a NB8A turbo'ed.
Have run from 7-14psi for nearly 18 months.
Currently running rich at 12 psi 168kw atw.
Has put out 187kw atw on dyno but struggled to run smoothly
at cold start.
No bottom end work done. Admittedly in that 18 months I have never
stomped on it in first gear or dropped the clutch at high revs. Oh yeah
the clutch has been built up to 1780 lb pressure plate clutch, 700 standard.
Only once has another driver gunned it in first and second gear. If I had known he
was going to do it I would have said don't do it:)
I only ever use the torque once I am into 2nd gear and have got past the wheelspin stage.
How long will the engine last no idea. Should you run less boost and less power. I am sure the answer to that question is Yes. A lot of people have commented that they are surprized that my car as not blown up. With so much power I find no need to boot it.
I believe the gearbox is probably the weakest link in the chain. Touch wood sofar no problems. I have heard it is good for around 165kw atw. The cost of building up the engine and the length of time off the road has deterred me from going down that route.
Cheers Novice1

[project.r.racing]

If Familia engines are anything to go by, then pushing more then 14psi regularly, will result in bent rods and holes in blocks. 17psi would kill the engines pretty quickly.

[SE10S]

If Familia engines are anything to go by, then pushing more then 14psi regularly, will result in bent rods and holes in blocks. 17psi would kill the engines pretty quickly.

is that 14psi on the standard turbo ????
i am upgrading the turbo to a 3076r so wanna know how much wiggle room i have before kaboom lol

[project.r.racing]

doesn't matter what turbo it is. you push too much pressure into the engine, it will go kaboom!

[SE10S]

doesn't matter what turbo it is. you push too much pressure into the engine, it will go kaboom!

Yeah i know thats why i was asking what a people experiences

[MINX]

SE10S

Where are you based?

All the info you need about SEs (MSMs) is here
http://www.mazda-speed.com

and here
http://www.flyinmiata.com/tech/MSM_upgrades.php

No need to reinvent the wheel.

[NitroDann]

doesn't matter what turbo it is. you push too much pressure into the engine, it will go kaboom!

PLEASE,

If you dont know what your talking about dont give advice in thread relating to peoples engines.

Boost isnt just boost.
When the air fuel mix combusts the engine sees well over 1000 psi during combustion, this is how the engine makes power, even just turning the motor over to start it makes 200psi just cranking with no spark. Its doesnt work "like 17psi will blow it, hurr durr".

Its combustion pressure that will break things, combustion pressure is what dictates torque, more pressure, more torque.
If you have a small inefficient turbo pushing 17psi with no intercooler, it might only be flowing as much air *MASS* as a larger more efficient turbo with water injection and a large intercooler does on 5 psi. This air MASS is the actual amount of molecules of air that your engine uses to burn with fuel and make power.

More air mass equals more torque (by adding more fuel and making more combustion pressure...yes thousands of psi).
The limit of B6 and Bp bottom ends is the rods first, both engines use the exact same rods, and they both have a safe limit that you can get away with for years of about 250rwFT/Lb. If you have big cams and make this torque at 8000rpm, you will make double the power of the bloke who only makes that torque at 4000rpm.

TL,DR Its not horsepower that breaks bottom ends, its torque. PSI and horsepower does NOT equal torque.

Dann

[SE10S]

15psi limit on any turbo on the stock rods. Rods will start to go at 200rwkw pistons at 220rwkw.

A 3076 is way too big for a stock 1.8 bottom end, even on a built 2.0 it will be laggy. Unless you are shooting for 400rwhp+ its way too much turbo, a 2560 or 2860rs is a much better choice for a stock bottom end.

What is your horsepower goal?

Cheers thats what i wanted to know, yeah it is a bit big for the standard bottom end but i wanted to get all the fab work done before i get a built bottomend, the goal is 400 whp+ should make it a bit of fun

[greenMachine]

Lots of things break engines, but I think you will find that the real killer is detonation, especially the sort that you can't hear (or don't recognise). Don't go for a highly agressive tune with as much timing advance as you can. Run a knock sensor if you really must push the limits, preferably one that pulls timing on knock, and be careful about the fuel you use. I assume you will be cleaning up the combustion chambers to (amongst other things) eliminate hotspots that might trigger detonation.

BPs are known for (relatively) weak rods, so best to play safe. I see you are planning a built bottom end, I suggest that you do it sooner rather than later.

The next weak link will be the gearbox. Do a search on here, but the short answer is an SE box and/or Redline Shockproof. Or a new gearset, 300kw (at the wheels?) is probably too much for an SE box, but I am only guessing. If you are going drag racing, the whole drive train will need a good look - some of Minx' sites should have some answers for you, but also see miatanet.com and miataturbo.net

[SE10S]

Lots of things break engines, but I think you will find that the real killer is detonation, especially the sort that you can't hear (or don't recognise). Don't go for a highly agressive tune with as much timing advance as you can. Run a knock sensor if you really must push the limits, preferably one that pulls timing on knock, and be careful about the fuel you use. I assume you will be cleaning up the combustion chambers to (amongst other things) eliminate hotspots that might trigger detonation.

BPs are known for (relatively) weak rods, so best to play safe. I see you are planning a built bottom end, I suggest that you do it sooner rather than later.

The next weak link will be the gearbox. Do a search on here, but the short answer is an SE box and/or Redline Shockproof. Or a new gearset, 300kw (at the wheels?) is probably too much for an SE box, but I am only guessing. If you are going drag racing, the whole drive train will need a good look - some of Minx' sites should have some answers for you, but also see miatanet.com and miataturbo.net

Thanks , yeah i have found from a few guys i have been talking to they are best before 220rwkw-230rwkw , theres always the freak engines that may play for a bit longer but i just keep it under that for the time being , but it all in tune like anything with turbo motors, i have been playing with rotarys for the last 10 years so i know all about not letting it go near detonation very well,

Gearbox wise i didnt think it would like that power very much but i have a dogbox here that was in one of my old rx7s which i have only eyeballed at the moment but looks like it could go in with very little stress, but i am not a big fan of the redline shock proof stuff, and diff wise was looking at the rx7 diffs to but i just see how it goes with the standard diff and maybe upgrade the axles, because the car will be used for some drag racing but more circuit stuff

[NitroDann]

15psi limit on any turbo on the stock rods. Rods will start to go at 200rwkw pistons at 220rwkw.

A 3076 is way too big for a stock 1.8 bottom end, even on a built 2.0 it will be laggy. Unless you are shooting for 400rwhp+ its way too much turbo, a 2560 or 2860rs is a much better choice for a stock bottom end.

What is your horsepower goal?

This still isnt right, read my post, it may be that 15psi on the stock turbo is the limit (yeah thats about right), but with water injection it might be 13 psi, a bigger turbo and water injection it might be 10 psi.

Dont just deal in absolutes with someone asking advice about his engine, if he throws a large frame garrett on there and boosts 15 psi with his new upgraded intercooler that is NOT the same as 15psi on a hot day from his stock turbo. Its much more.

Dann

[SE10S]

15psi limit on any turbo on the stock rods. Rods will start to go at 200rwkw pistons at 220rwkw.

A 3076 is way too big for a stock 1.8 bottom end, even on a built 2.0 it will be laggy. Unless you are shooting for 400rwhp+ its way too much turbo, a 2560 or 2860rs is a much better choice for a stock bottom end.

What is your horsepower goal?

This still isnt right, read my post, it may be that 15psi on the stock turbo is the limit (yeah thats about right), but with water injection it might be 13 psi, a bigger turbo and water injection it might be 10 psi.

Dont just deal in absolutes with someone asking advice about his engine, if he throws a large frame garrett on there and boosts 15 psi with his new upgraded intercooler that is NOT the same as 15psi on a hot day from his stock turbo. Its much more.

Dann

yeah but i was just assuming he was talking about standard turbo and engine, just wanted to get a bit of a idea how much room to move i have with it as i am a novice with these engines, so thanks for all the help guys its greatly appreciated

[Novice1]

15psi limit on any turbo on the stock rods. Rods will start to go at 200rwkw pistons at 220rwkw.

A 3076 is way too big for a stock 1.8 bottom end, even on a built 2.0 it will be laggy. Unless you are shooting for 400rwhp+ its way too much turbo, a 2560 or 2860rs is a much better choice for a stock bottom end.

What is your horsepower goal?

Cheers thats what i wanted to know, yeah it is a bit big for the standard bottom end but i wanted to get all the fab work done before i get a built bottomend, the goal is 400 whp+ should make it a bit of fun

Ok rods at 200rwkw , pistons at 220rwkw. What about gearbox?
I have a eboost2 installed and can choose from 6psi or 12 psi. 99 percent of the time car runs on low boost. I may go months without hitting SP2 or high boost.
Currently my car puts out 168rwkw at 12 psi and 417 newton metres of torque. Perhaps my car has not detonated as a) high boost is very rarely used b) even on high boost I never throttle it from a standing start. Recommendations for what gearbox to use if I am pushing the boundaries. Can't see myself going over 200rwkw but 180 plus is well within my cars reach.
Cheers Novice1

[NitroDann]

350hp or so on the 6 speed. The worlds highest power 1.6 makes well over 400 on a 5 speed, but he only does highway pulls.

Dann