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Posted: **Nov 03, 2008 5:50 PM**

Thanks guys! Also, i know that it is really important to have the turbo chosen before building, but what if i want to change it later?

Say i go for a T04E with a 50 trim, but later on want to upgrade to a T04E 60 trim. Are the actual dimensions of the turbo going to be the same? Or does the increase in the fan size change the turbo dimensions?

I have a feeling that ill be building this kit around a T04E with 57 trim and stick with it though. Itd be great to score a GT-series garrett, but we'll see how things go!

Thanks again guys, ill be sure to check out the 103 section as ive got it bookmarked!

-Jeff

Posted: **Nov 04, 2008 1:06 AM**

Typically you cannot just swap compressor wheels as the inducer diameters are different between wheels and would require a different cover or machining of your old cover. The exducer diameters are also different and possibly the tip height which also may require machining.
IMO, a T04E 57 trim is a bit small for an m30. All of the following maps are plotted out for 350bhp with redline at 6500. You are off into the choke region of the map. No good.
57 Trim

The 60 trim, while not perfect is better suited.
60 Trim

Now, compare this to a T04B 60-1 which is a better match still.
60-1

Now, lets plot a couple of GT series turbos.

Lets look at the GT3582R which is a pretty sweet match and a peak efficiency island of 79%.
GT3582R

And finally the GT40 54 trim compressor wheel which is also excellent.
GT40 54 Trim

I hope this helps give you a visual idea of the usefulness of compressor maps and what a good match looks like plotted. It also lets you visualize a compressor that is too small.

Posted: **Nov 04, 2008 12:51 PM**

Those maps look like they go to 45 lbs/min, so that'd be at least 450bhp, correct?

Posted: **Nov 04, 2008 1:31 PM**

I just used their mapping program to rattle those off and ya, I think they are a bit high in practice. Not my favorite, but I was in a hurry. The rule of thumb of bhp=lb/minx10 usually holds pretty true.
Their x axis airflow calcs are using BSFC in the equation:
measured in lb/min, airflow = (HP target) x (air/fuel ratio) x (BSFC/60) where BSFC is lbs fuel / (hp x hr) instead of just raw airflow values. I think I used a BSFC of .55.

Posted: **Nov 05, 2008 1:12 AM**

Great info! Thanks for the visualization of it. Ill do a little more reading on the compressor maps to get a better understanding of how to read them.

Thanks again!

-Jeff

Posted: **Nov 05, 2008 1:21 AM**

Hey Jeff, I'm using the T04e-60. I haven't turned up the boost high enough to push the limits of the compressor.... but I can make boost below 2k rpm and I'm seeing 10psi around 3K.

Power still builds linearly to 6.5K rpm. Its a good turbo for the cost. If I tear it apart in the future I'll go with the GT series but for a first attempt its given me nothing but smiles.

Remember another thing to consider when plotting the compressor map is the engine's compression ratio. The higher compression ratio, the lower the boost threshold will be.

Posted: **Nov 05, 2008 11:25 AM**

For any reasonably sized turbo, you should fully spool by peak torque.

Posted: **Nov 05, 2008 2:31 PM**

turbodan wrote:For any reasonably sized turbo, you should fully spool by peak torque.

Absoulutely true.

Posted: **Dec 31, 2008 11:01 AM**

can someone post what I need to get for the Megasquirt setup? I went on the MS site and noticed many options and have read here and there about a board that gets integrated to the factory computer...does this sound right? I tried the search function, but could not come up with previous posts about the system. thanks!

Posted: **Dec 31, 2008 11:08 AM**

alijonny wrote:can someone post what I need to get for the Megasquirt setup? I went on the MS site and noticed many options and have read here and there about a board that gets integrated to the factory computer...does this sound right? I tried the search function, but could not come up with previous posts about the system. thanks!

I am working on a MS FAQ and it will have all the info you need. It will be up this weekend. If you need it sooner PM me.

Posted: **Dec 31, 2008 11:13 AM**

Big Bronze Rim wrote: I am working on a MS FAQ and it will have all the info you need. It will be up this weekend. If you need it sooner PM me.

Speaking of MegaSquirt...
I was trying to look at coilpacks as an option to replace the distributor. Is this only an option with aftermarket engine management, or can you run it off your motronic? I'm thinking that you have to have something like MS, but I couldn't find any conclusive posts/threads. Would probably do MSD Coil and box, too.

Posted: **Dec 31, 2008 11:26 AM**

Motronic can't run anything but a single coil and a distributor. It works with an MSD box, but thats still just using a single coil and a distributor.

Wasted spark, coil on plug, etc. are standalone options only.

Posted: **Dec 31, 2008 3:13 PM**

turbodan wrote:Motronic can't run anything but a single coil and a distributor. It works with an MSD box, but thats still just using a single coil and a distributor.

Wasted spark, coil on plug, etc. are standalone options only.

Well put.

Posted: **Jan 07, 2009 6:21 PM**

Great write up, it's much appreciated.
I really can understand most of this, but when it gets down to numbers, fuel maps, compressor maps... That's where I start to get overwhelmed. I really feel like I could get out there and do this (once the money tree blooms) but it's the tuning that concerns me. Mostly because tuning, or I should say a good tune, seems to go hand in hand with the understanding of the maps. I mean, I'm comfortable turning a wrench, mocking up and welding the 3" exhaust, but I aint got dem der book smarts...
So how far in depth do you (or should say I) really need to understand the calculations behind the scenes? Is that something I really need to wrap my mind around before I start planning a build? I don't want to be the guy that's posting about wanting 300hp, and no clue what the corresponding injector or compressor size is...
Dammit, that's what I'm doing right now.

I digress... thanks for the post.

Posted: **Jan 07, 2009 9:04 PM**

deucestudios wrote:Great write up, it's much appreciated.
I really can understand most of this, but when it gets down to numbers, fuel maps, compressor maps... That's where I start to get overwhelmed. I really feel like I could get out there and do this (once the money tree blooms) but it's the tuning that concerns me. Mostly because tuning, or I should say a good tune, seems to go hand in hand with the understanding of the maps. I mean, I'm comfortable turning a wrench, mocking up and welding the 3" exhaust, but I aint got dem der book smarts...
So how far in depth do you (or should say I) really need to understand the calculations behind the scenes? Is that something I really need to wrap my mind around before I start planning a build? I don't want to be the guy that's posting about wanting 300hp, and no clue what the corresponding injector or compressor size is...
Dammit, that's what I'm doing right now.

I digress... thanks for the post.

I can certainly understand the frustration. I'm an engineer and I still get confused and frustrated simply working out the numbers. Anyone on here who has tuned their own system will know that there is no "perfect" size for anything. whether it be injectors, compressors, exhaust size, whatever. What you need to do is first set a goal. Your goal should be to make X amount of power while spending Y amount of money. From there, you can go through the different stages and aspects of the system (with the help of everyone in the F/I section) and find a good range to be. Once you know that range, you can start selecting the components that fit into that range.

If your building your own system from scratch, the more planning and understanding there is from the beginning, the less headaches there are in the future.

Posted: **Nov 05, 2009 11:54 AM**

To keep this within the FAQ as it´s related to M30´s specifically.

At what torque output(cylinder pressure) level would one expect head lifting to occur on a B34 with stock headbolts?

M20´s seem to show head lifting to occur around 250-300lbs of torque from what I have seen.

Posted: **Nov 05, 2009 12:25 PM**

I was making 360 ft-lbs uncorrected with the stock M20 head gasket and bolts. It put up with over 400 ft-lbs for a few more months before it blew the HG.

Its really more of an issue with detonation than power output. I guess thats the moral of the story.

Posted: **Nov 05, 2009 1:05 PM**

Ok, let´s put that down as a known fact for information seekers.

If anybody has similar known knowledge about the M30
then that´d be great.

Posted: **Nov 09, 2009 6:42 PM**

Any thoughts?
when does the M30 head start to lift

Posted: **Nov 09, 2009 6:47 PM**

Gunni wrote:Any thoughts?
when does the M30 head start to lift

I made 375rwtq with an untouched engine. Drove many many miles. 20 runs at the dragstrip. Then it blew when I upped it some more. The day it died it made 417rwtq on the dyno.

Posted: **Feb 09, 2010 1:06 PM**

-Forced induction: By far the most effective means of increasing power output, with tremendous potential available for far less than the cost of a NA stroker engine. A stock engine with head studs will reliably support over 20 psi with intercooling, a good tune and a sufficiently large turbine. Standalone injection should be considered mandatory for boost pressures over 1 bar. The bottom ends are very robust and will be the last parts to sustain damage if detonation occurs. The head gasket will fail first, which can crack the cylinder head if the engine is run for very long in that condition. They tolerate a considerable amount of detonation at lower boost pressures but become more sensitive as boost increases. The driver must listen carefully to the engine to avoid damage if detonation occurs. Aftermarket MLS head gaskets resist detonation slightly better which can result in damage to the piston ring lands in the event of severe, sustained detonation. Even slight detonation is audible with a full exhaust system while moderate detonation can usually be heard over an "open dump" wastegate.

Some awesome cool guy just wrote that up on wikipedia in the M20 section. Seems relevant...

Posted: **Feb 12, 2010 1:07 PM**

psi is irrelevant as we know and it´s not really a guideline either for the torque to be made.

standalone shouldn´t be considered mandatory. It´s ideal, but shouldn´t be mandatory..

It just sounds to general and not specific enough.

I can attempt to venture that a stock M20 8.8:1 compression (ARP) will be able to hold about 400lbs of torque as a guideline.
That´s more along the lines of actual guideline rather then 20psi or 10psi.

Posted: **Feb 12, 2010 1:52 PM**

It should be general, its just a blurb on wikipedia. And as you know, torque and boost are related to each other. The limit as I know it isn't the strength of the motor but the threshold of detonation, which isn't a factor of torque output. I've never blown a head gasket because I was making too much torque.

Posted: **Feb 14, 2010 8:04 AM**

The threshold of detonation comes from cylinder pressure/temp.
Which is directly related to torque output.

Posted: **Feb 16, 2010 6:06 PM**

Gunni wrote:The threshold of detonation comes from cylinder pressure/temp.
Which is directly related to torque output.

Correct, and we increase combustion chamber pressures by increasing boost.

Torque will vary depending on stroke/rod length as well, whereas the onset of detonation should be more consistent for the same compression ratio and boost pressure. Feel free to look at it completely backwards though if you prefer.

Posted: **Feb 17, 2010 1:50 AM**

turbodan wrote: Torque will vary depending on stroke/rod length as well,

Are you talking stroke to rod ratio (or rod to stroke ratio if you like), the stroke length and the rod length independently affecting torque or something else all together?

Posted: **Feb 17, 2010 10:17 AM**

I'm talking about bottom end geometry. What else would I be talking about?

Posted: **Feb 17, 2010 2:44 PM**

Are you saying that stroke dictates torque production (I.E. more stroke = more torque)?

Posted: **Feb 17, 2010 2:54 PM**

Canuck YYC wrote:more stroke = more torque?

That is my understanding.

Posted: **Feb 17, 2010 2:56 PM**

I was following what you guys were saying, and I looked up what you guys were discussing. So maybe this finding will help. I believe this is what Dan was saying.

"In the simplest sense, torque is related to the stroke of the piston and the stroke is determined by the crankshaft. The longer the stroke, the more torque. The stroke is determined by how far the connecting rod journal is offset from the centerline of the crankshaft. If the journal is close to the centerline, it makes a smaller circle in relation to that centerline and thus a short stroke. If it is further out, it makes a larger circle resulting in a longer stroke.
The further away the connecting rod journal is from the centerline, the more torque is applied. Just as a longer lever can lift more weight, a longer stroke applies more torque."

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