FS-DE Extended Specs

[igdrasil]

Extended Engine Specs:

Bore & Stroke: 83 x 92mm (3.62" long stroke)
Compression Ratio: 9.1:1
Displacement: 1991cc
Mean Piston Speed: 0.167 * 3.62 * 6500 = 3929 ft/min at 6500rpm
- As a benchmark, MPS
- under 3,500 ft/min - Good reliability
- 3,500-4,000 ft/min - Stressing
- over 4,000 ft/min - Very short lived

Ring Loadings
Top-rings must balance high-rpm capability and wear, a thin ring allows high-rpm capability, too thin and wear becomes an issue. With reduced crank angles from a short stroke ring wear is reduced. A 1.5mm ring is beneficial over a 1.0mm ring for high-rpm.

Maximum-Piston-Acceleration (MPA):
- top-ring - 1.17mm/0.046"
- MPA Permitted = 105,000ft/sec^2
- MPA Experienced = 70,157ft/sec^2
MPA = (rpm^2 * stroke"/2189)*(1/2A), A = ratio between rod-length-between-centres to stroke. rod-centre-dist = 135mm; stroke = 92.0mm; A = 1.47
= (6500^2*3.62/2189)*(1.2*1.47) = 51,354 ft/sec^2
rod pin diameter: .748
BE Bore: 2.008
rod lenght: 5.320 (135mm)
BE width: .860

Intake Valves
- Diameter: 33mm
- Base circle: 35.052mm
- Lobe height: 43.700mm
- Lift: 8.6487mm
- Duration: 230 @ 0.003"
- Opening: 2 BTDC
- Closing: 48 ABDC

Exhaust Valves
- Diameter: 27.5mm
- Base circle: 35.052mm
- Lobe height: 43.225mm
- Lift: 8.1737mm
- Duration: 230 @ 0.003"
- Opening: 48 BBDC
- Closing: 2 ATDC

Direction of engine rotation: Clockwise

Intake PORT Dimensions:
Height - 31mm,
Width - 49.5mm

 

[Greensleeper]

Thanx!

 

[Mike R]

So, at redline the pistons are almost ready to come apart when it's stock? That's not good.

 

[scorch70]

Extended Engine Specs:

Bore & Stroke: 83 x 92mm (3.62" long stroke)
Compression Ratio: 9.1:1
Displacement: 1991cc
Mean Piston Speed: 0.167 * 3.62 * 6500 = 3929 ft/min at 6500rpm
- As a benchmark, MPS
- under 3,500 ft/min - Good reliability
- 3,500-4,000 ft/min - Stressing
- over 4,000 ft/min - Very short lived

Ring Loadings
Top-rings must balance high-rpm capability and wear, a thin ring allows high-rpm capability, too thin and wear becomes an issue. With reduced crank angles from a short stroke ring wear is reduced. A 1.5mm ring is beneficial over a 1.0mm ring for high-rpm.

Maximum-Piston-Acceleration (MPA):
- top-ring - 1.17mm/0.046"
- MPA Permitted = 105,000ft/sec^2
- MPA Experienced = 70,157ft/sec^2
MPA = (rpm^2 * stroke"/2189)*(1/2A), A = ratio between rod-length-between-centres to stroke. rod-centre-dist = 135mm; stroke = 92.0mm; A = 1.47
= (6500^2*3.62/2189)*(1.2*1.47) = 51,354 ft/sec^2
rod pin diameter: .748
BE Bore: 2.008
rod lenght: 5.320 (135mm)
BE width: .860

Intake Valves
- Diameter: 33mm
- Base circle: 35.052mm
- Lobe height: 43.700mm
- Lift: 8.6487mm
- Duration: 230 @ 0.003"
- Opening: 2 BTDC
- Closing: 48 ABDC

Exhaust Valves
- Diameter: 27.5mm
- Base circle: 35.052mm
- Lobe height: 43.225mm
- Lift: 8.1737mm
- Duration: 230 @ 0.003"
- Opening: 48 BBDC
- Closing: 2 ATDC

THanks igdrasil, great info!


scorch70

 

[SpicyMchaggis]

thanks for the write up! good info.

 

[mp3moose]

So, at redline the pistons are almost ready to come apart when it's stock? That's not good.

Yeah, wtf mate?

 

[Focus]

So, at redline the pistons are almost ready to come apart when it's stock? That's not good.

Actually it's the rods that are stressing more then the pistons are.

 

[mp3moose]

^true, but if the stress is that high on the pistons at near redline how much worse is it on the rods?

 

[Micah]

hmm.... guess I had better stop flooring my poor AT ES, first gear gets up to just a hair before red - then the tranny shifts.

Where did this info come from anyway?

 

[mazdaowner123]

^true, but if the stress is that high on the pistons at near redline how much worse is it on the rods?

Maybe I should have used second gear at the last autox...

~brian

 

[Kooldino]

So, at redline the pistons are almost ready to come apart when it's stock? That's not good.

Who determined the stress ratings?

 

[p5sundevil]

im thinkin the comments were based on assumptions.....we have made some progress in the NA forums in trying to find out the potential of the stock pistons, since for NA we would be raising compression and redline which just makes things worse.....in the end for FI forged slugs are best and an all out NA app will require forged also, forged aluminum or titanium would be best and as things go with every other part of the car those best routes are most expensive.

here are a couple threads from one of our NA gurus =P installshield....
http://www.msprotege.com/forum/showthread.php?t=70918

http://www.msprotege.com/forum/showthread.php?t=78516

http://www.msprotege.com/forum/showthread.php?t=78404


These specs will be most helpful igdrasil, much appreciated...and bookmarked.

 

[iluvmacs]

Thank you so much for posting those specs!!!

If I may chime in about the piston speeds, that should have a lot to do with the exact alloy being used and it also has to do with the cross-sectional area of the Con-rod. I'd like to know for what specs those "stressing/short lived" justifications are for.

 

[Installshield 2]

Excellent Excellent post man...seriously good info for anyone serious about building an FS...

Some confusion will probably arise based on the MPS benchmarks...mostly because they are a very general assumption on engine reliability...and I have seen those ratings before, so I don't think its anything new...

One thing to bare in mind when concerning engine reliability at certain piston speeds (and hopefully everyone reading has already grasped that this is a radically different notion than the rpm of the crank) is the material of which the rods in question (the wrist pin crowning of the pistons are usually much stronger than the overall rod itself...as long as you are not using a cast piston with a forged rod...so this is mostly concerning the integrity of the rods) are constructed out of...different materials have completely different tensile strength rating, which is basically a indication of how much stress it can take before beginning to stretch, warp, rip apart, etc...certain manufacturing processes create rods that can tolerate different types of stresses...

Now this is the main point...the damage the mean piston speed does on any engine, is correlated directly with the mass of the piston/rod assembly...high mass parts will not tolerate high piston speeds nearly as well...That 3500 ft/sec being the top limit for reliability is completely false on 4cylinder engines...on a 6.0L V-8? probably...and many motorcycle engines pull nearly 5000ft/sec easily...3500 is much lower than what a well built strong internalled 2.0L engine can handle...also plenty of people have beat the piss out of an FS for over 100,000 miles, and I have not once heard of anyone saying they needed an engine rebuild because of stretched or compressed rods because of MPS wear...

As far as only the FS: We have tiny bore pistons, that are pretty low mass in the first place, and tiny short little rods...all of which that make a relatively low mass assembly...we do have high piston speeds stock, but again its not nearly as big of an issue as some people make it to be with an engine such as ours...the most important outcome that all this means for an FS though, is that we will never see 9 grand reliably...you could do it for a one off racing engine that gets rebuilt often, but for a street car it is simply too high...

also an important part is the the FS-ZE's specs...in which it was determined to be perfectly reliable at 7200rpm...and you can pull that easily with the stock internals...anything much beyond that will quickly deteriorate the stock recipricating assembly, including the forged crank, that is busy wrangling the heavy ass stock internals around...

Just trying to point out that you shouldn't get worried at all at the stock redline with the stock internals...you will get plenty of reliable miles out of it as far as that is concerned...if anything be worried about the stock oiling system...

If you are looking for increasing the revs...look into forged aluminum as the rod/piston material...its not as expensive as titanium, but still saves tons of mass...lb for lb forged aluminum is better than the stock cast pieces, allowing high weight savings to the recipricating assembly...overall reducing internal stress by a large margin, and allowing as much as 800-900 more rpm reliably...

the route I took involved also increasing the rod ratio a little, bringing it to around 1.56 from what I remember...right at what a B18 has...this creates a lower piston acceleration relative to the engine rpm (sort of...not getting into that in this post, it changes behaviour at the ends of the stroke)...but I didn't do it so much for the reliability; more because it will help with high end breathing when matched with the proper cams...

 

[Installshield 2]

Here is a link for a lot of posts from people that truely know their poop...I realize I may not have the credentials to say "this is nothing to worry about"...so I will link you to guys that can say that...

read every post damn it...

http://www.eng-tips.com/viewthread.cfm?qid=85349

 

[BlueWolfCry]

damn good info igdrasil and installshield 2. I floor it all the time..so I'm glad you mentioned that installshield, thanks!

 

[Greensleeper]

Thanx Installshield2....

I see that in my NA fantasy:

- Un-lipped throttle body
- Ported and ''V-flappy pollution s*** removed'' intake manifold
- Custom ground AWR cams (read: BIG)
- Eibach EVS valve springs
- FS-ZE 10.4:1 pistons
- Installshield2-fabricated forged aluminium rods
- MAM fuel rail
- MPI tuner
- MAM oil pan
- Raised redline to 7 400 rpm (MPI can do that no?)

200 crank hp, ALL DAY, EVERY DAY, no?

 

[igdrasil]

This is WHY....the S2000 can rev up to 10krpms having same displacement as our motors.

<TABLE cellSpacing=0 cellPadding=3 width="90%"><TBODY><TR><TD align=left bgColor=#efefef>Bore x stroke:</TD><TD align=left bgColor=#ffffff colSpan=2>87.00mm 84.00mm</TD></TR></TBODY></TABLE>

 

[hi-perf]

This is WHY....the S2000 can rev up to 10krpms having same displacement as our motors.

<table cellpadding="3" cellspacing="0" width="90%"><tbody><tr><td align="left" bgcolor="#efefef">Bore x stroke:</td><td colspan="2" align="left" bgcolor="#ffffff">87.00mm 84.00mm</td></tr></tbody></table>

that doesnt necessarily mean if you de-stroke an FS-DE (FP-DE) that it will rev to 10k reliably.

 

[jaman]

This is WHY....the S2000 can rev up to 10krpms having same displacement as our motors.

<table cellpadding="3" cellspacing="0" width="90%"><tbody><tr><td align="left" bgcolor="#efefef">Bore x stroke:</td><td colspan="2" align="left" bgcolor="#ffffff">87.00mm 84.00mm</td></tr></tbody></table>

10k rpm? as in one time for 0.5s or as a new red-line? damn, that is pretty high!