Notices
924/931/944/951/968 Forum Porsche 924, 924S, 931, 944, 944S, 944S2, 951, and 968 discussion, how-to guides, and technical help. (1976-1995)
Sponsored by:
Sponsored by:

Hybrid NA motor build

Thread Tools
 
Search this Thread
 
Old 11-09-2018, 03:07 AM
  #1  
Dwizle
Racer
Thread Starter
 
Dwizle's Avatar
 
Join Date: Sep 2013
Location: Misawa AFB
Posts: 287
Received 18 Likes on 16 Posts
Default Hybrid NA motor build

So after reducing the second motor in my '86na to scrap earlier this year #2 bearing failure at hi speed...
I decided on doing a hybrid stroker engine similar to refresh951 based on Blown944's design
https://rennlist.com/forums/944-turb...ker-build.html
Build Specs
Pistons: Speed Pro hypereutectic 383 stroker pistons - H860CP. +30 bore. -5cc
Rods: 2G DSM 95 - 99 Mitsubishi Eclipse OEM Connecting Rod 4g63T Turbo.
Sleeves: LA Sleeve p/n FL3209
Cometic Head Gasket C4273-040; MLS Stainless .040" 103.0mm bore.
83-89 Porsche 944 Crankshaft Crank Shaft - 2.5L Non-Turbo
Using the same calculator Refresh951 used on eagle rod dot com http://www.eaglerod.com/index.php?op...tpage&Itemid=1
with almost the same number as Refresh951 except I will have -5cc flat top piston vice his dished piston n not sure on the head cc but I should have a 10.58-1 to 10.09- 1 compression ratio
deck height and piston volume might change if machine shop cut the valve reliefs deep enough to make it a non-interference engine n the whole rotating assy balanced
will Be ran with MS II or MS III stand-alone or the F9tech dme http://www.ftech9.com/new-products/porsche-944-dme
So question what kinda Hp or Torque gains might I expect? IF ANY?

Old 11-09-2018, 03:14 AM
  #2  
odonnell
Rennlist Member
 
odonnell's Avatar
 
Join Date: Nov 2012
Location: Houston TX
Posts: 4,774
Received 69 Likes on 50 Posts
Default

Seems like a lot of money and effort just to keep it NA.
Old 11-09-2018, 07:58 AM
  #3  
Tiger03447
Rennlist Member
 
Tiger03447's Avatar
 
Join Date: Apr 2011
Location: Elizabethton,TN
Posts: 3,422
Received 153 Likes on 134 Posts
Default

Just get another engine and then dry-sump it..Should eliminate #2 bearing problem. Save some $$...You might even consider (OH horrors!) an external oil line to feed just #2 bearing since the oiling system is somewhat suspect in these motors. just a thought.
Old 11-09-2018, 08:35 AM
  #4  
MAGK944
Nordschleife Master
 
MAGK944's Avatar
 
Join Date: Jun 2007
Location: Palm Beach, Florida
Posts: 6,769
Received 298 Likes on 231 Posts
Default

If your aim is to reduce #2 bearing failure by spending a bunch of cash with relatively little performance gain, then yes that build will do it
Old 11-09-2018, 09:49 AM
  #5  
Gage
Rennlist Member
 
Gage's Avatar
 
Join Date: Aug 2012
Posts: 1,630
Received 364 Likes on 295 Posts
Default

The (snarky) answer to the hp and tq question is 0 and 0 without a cylinder head and camshaft��
Seriously though, to reap the benefit of increased displacement, especially without forced induction, the air flow in and out of the engine are the most critical variables to be solved.
Old 11-09-2018, 10:25 AM
  #6  
951and944S
Race Car
 
951and944S's Avatar
 
Join Date: Dec 2001
Location: New Orleans/Baton Rouge
Posts: 3,930
Received 65 Likes on 56 Posts
Default

Originally Posted by Gage
The (snarky) answer to the hp and tq question is 0 and 0 without a cylinder head and camshaft��
Seriously though, to reap the benefit of increased displacement, especially without forced induction, the air flow in and out of the engine are the most critical variables to be solved.
Not really so snarky, there is no way to answer OP's question without knowing info about camshaft and recalculations due to rod angle/stroke/piston speed. etc., xx power level requires xx cfm support, etc., etc., etc.

T
Old 11-09-2018, 10:31 AM
  #7  
951and944S
Race Car
 
951and944S's Avatar
 
Join Date: Dec 2001
Location: New Orleans/Baton Rouge
Posts: 3,930
Received 65 Likes on 56 Posts
Default

Originally Posted by Tiger03447
Just get another engine and then dry-sump it..Should eliminate #2 bearing problem. Save some $$...You might even consider (OH horrors!) an external oil line to feed just #2 bearing since the oiling system is somewhat suspect in these motors. just a thought.
There have been so so many "theories" as to the #2 problem there could probably be a book written about it.

Your idea of an external line isn't so crazy.

Most people just state vaguely that "oil system sucks" or "pump will never work past 6000 rpms", etc., etc.

If the main source of problems would be the pump, then the farthest journal from the pump would be the one failing, not #2.

T

Old 11-09-2018, 11:29 AM
  #8  
V2Rocket
Rainman
Rennlist Member
 
V2Rocket's Avatar
 
Join Date: Jan 2007
Location: Nashville, TN
Posts: 45,588
Received 662 Likes on 515 Posts
Default

you're adding ~12% more displacement so you should reasonably be able to expect~12% more torque and maybe 12% more power, if the cylinder head can still feed the extra displacement at higher RPMs.
"technically" keeping the head/valves the same size with more displacement underneath should lower the max RPM range but i don't know that the 944NA is near its limit regarding valve size or not, i would think not.

it might be like the Ford 4.6 vs 5.4 (2-valve) engines...they used the same heads and cams and pistons, but the crank/rods/block were "bigger" to suit the 5.4 stroke....end result the 5.4 made proportionally more Torque than the 4.6 but they made right about the same HP overall.
Old 11-09-2018, 12:46 PM
  #9  
Dwizle
Racer
Thread Starter
 
Dwizle's Avatar
 
Join Date: Sep 2013
Location: Misawa AFB
Posts: 287
Received 18 Likes on 16 Posts
Default

For
Originally Posted by Gage
The (snarky) answer to the hp and tq question is 0 and 0 without a cylinder head and camshaft��
Seriously though, to reap the benefit of increased displacement, especially without forced induction, the air flow in and out of the engine are the most critical variables to be solved.
Originally Posted by 951and944S
Not really so snarky, there is no way to answer OP's question without knowing info about camshaft and recalculations due to rod angle/stroke/piston speed. etc., xx power level requires xx cfm support, etc., etc., etc.

T
Stock Cam with a 4 deg advance I have a turbo header a friend gave me or maybe an aftermarket header but start out a stock one n maybe finish the Mustang TB install. With MS system the biggest limiting factor to airflow in the system is removed the airflow meter.
Max Rod angle 16.68deg
Rod Ratio 1.74:1
Mean Piston Speed @ 7000 rpm 65.8fps
I have roughly $1800 into it right now $1000 to the machine shop to start work and orders sleeves.
Pistons: Speed Pro hypereutectic 383 stroker pistons - H860CP. +30 bore. $176.99
Rods: 2G DSM 95 - 99 Mitsubishi Eclipse OEM Connecting Rod 4g63T Turbo. $135.00
Bearings /Misc: Cometic Head Gasket C4273-040; MLS Stainless .040" 103.0mm bore. $87.09
Porsche 924 944 Turbo REINZ Engine Block Gasket Set $149.70
MAIN BEARING SET STD. GLYCO Part# 944-101-901-00-AM $240.69
Haven't ordered rod bearings until machine shop says what size to order then will have them coated prob around $150
If I can get it done for less than the $3500 Refresh951 says it can be done for on a turbo it's worth it for me..

For those that say why not get another engine or why spend the money to keep it na. well I did get another engine that the PO says was rebuilt pulled to do an LS swap
had a shiny paint job on it that the balance shaft belt let go and wedged itself between the timing belt and the water pump 2 weeks after I installed it
and bent 3 out of 4 exhaust valve n 2 intake valves. $1000 for that motor #3 So if this works and I eliminate two of the Achilles heels of this motor I think its worth it.
If it was about the money most of us would have gotten rid of these cars a long time ago


Represh951 build numbers just that mine has a flat top piston so it has -5cc piston dome n 68cc head not sure about that. n divide engine size by 2 the calculator was set up for a V8
http://www.eaglerod.com/index.php?op...tpage&Itemid=1
Old 11-09-2018, 12:53 PM
  #10  
Dwizle
Racer
Thread Starter
 
Dwizle's Avatar
 
Join Date: Sep 2013
Location: Misawa AFB
Posts: 287
Received 18 Likes on 16 Posts
Thumbs up

Originally Posted by V2Rocket
you're adding ~12% more displacement so you should reasonably be able to expect~12% more torque and maybe 12% more power, if the cylinder head can still feed the extra displacement at higher RPMs.
"technically" keeping the head/valves the same size with more displacement underneath should lower the max RPM range but i don't know that the 944NA is near its limit regarding valve size or not, i would think not.

it might be like the Ford 4.6 vs 5.4 (2-valve) engines...they used the same heads and cams and pistons, but the crank/rods/block were "bigger" to suit the 5.4 stroke....end result the 5.4 made proportionally more Torque than the 4.6 but they made right about the same HP overall.
Thanks For the response
Old 11-09-2018, 07:15 PM
  #11  
jimmerp
Instructor
 
jimmerp's Avatar
 
Join Date: May 2011
Location: Nova Scotia
Posts: 101
Received 1 Like on 1 Post
Default

I like the idea. Better bearings, lighter rods, and a stroke increase. Add a good cam and enjoy.
Old 11-09-2018, 08:59 PM
  #12  
951and944S
Race Car
 
951and944S's Avatar
 
Join Date: Dec 2001
Location: New Orleans/Baton Rouge
Posts: 3,930
Received 65 Likes on 56 Posts
Default

Well, you seem to have all your ducks in a row, so, go for it.

T
Old 11-10-2018, 01:26 PM
  #13  
V2Rocket
Rainman
Rennlist Member
 
V2Rocket's Avatar
 
Join Date: Jan 2007
Location: Nashville, TN
Posts: 45,588
Received 662 Likes on 515 Posts
Default

Look up user Ish944, he did a 2.8 NA similar build with good results
Old 11-11-2018, 01:01 AM
  #14  
Dwizle
Racer
Thread Starter
 
Dwizle's Avatar
 
Join Date: Sep 2013
Location: Misawa AFB
Posts: 287
Received 18 Likes on 16 Posts
Default

Originally Posted by V2Rocket
Look up user Ish944, he did a 2.8 NA similar build with good results

Thanks
Old 11-11-2018, 03:20 AM
  #15  
The Forgotten On
Rennlist Member
 
The Forgotten On's Avatar
 
Join Date: May 2012
Location: Thousand Oaks California
Posts: 4,972
Received 318 Likes on 265 Posts
Default

People are building 5.9 liter 928 engines with the same size valves making well over 400 crank hp. You can get 400 hp easily with just 5 liters in a 928 so a 200 hp NA build would be fairly easy for the head to deal with.

The AFM is the main restriction anyway, going with a MAF conversion or a MAP sensor on a standalone would make the biggest difference to flow.


Quick Reply: Hybrid NA motor build



All times are GMT -3. The time now is 09:36 PM.