free hit
counters
Engine Rebuild/Upgrades - Engine/Ancilliaries - The Lotus Forums #ForTheOwners Jump to content


Engine Rebuild/Upgrades


Recommended Posts

So I am in the process of getting my V8 engine rebuilt, for normal driving.  I don't plan racing or running it too hard.  Are there any advantages of doing Piston upgrades, and are there any other recommended upgrades?

 

Obviously I don't want to upgrade to the point of having to upgrade the transmission just to upgrade something else.  I don't want to keep chasing the never ending upgrade path.

Link to comment
Share on other sites


Upgrade today to remove Google ads and support TLF.
  • Gold FFM

I'll be interested to see what other more seasoned V8 engine builders say but if it is just for normal driving then I expect it will be just fine with standard components.

cheers

-Chris

Link to comment
Share on other sites

@Joey4420 when my Oil Pressure Release Valve (PRV) failed and my engine suffered from oil starvation causing a spun conrod bearing, I had to dismantle and rebuild the engine.

I had to replace a lot of parts, including new oil pump, head bolts and head gaskets, which are not cheap.. Furthermore, the labor was going to be expensive.. So I decided I had my one and only chance to upgrade the cast pistons with CP Carillo forged items.. The price was right, and I decided to go ahead and do so..

My crankshaft was repaired and rebalanced based on the new pistons, and I am very happy now to know that my car has forged internals (the conrods are already forged steel, so is the crankshaft forged steel)...

So, even though I work with stock turbo pressure (I rebuilt the turbos, fitted K&N air filters, deleted cats and muffler - just straight pipes, and put Sport 350 ECU) I am very happy to know that my car now has much stronger internals than when it left the factory..

Just think that you get your one chance to put those pistons..

Of course you decide, but this is my opinion..

  • Like 1
Link to comment
Share on other sites

What is the scope and reason behind the rebuild?  Was something damaged or are you just re-freshing/overhauling the engine? 

In general, I would not recommend the outlay of upgrading parts if you are really only after a stock power output.  If you do not drive the car hard, then the stock components will be fine.   However, if you are already considering installing some new stock components (e.g. new pistons and liners), then do the math and investigate what additional expense to take some forged pistons.  In terms of advantages of forged pistons for stock output, there aren't really any.  In fact there is a theortical disadvantage in that the forged pistons do not include the Big end thrust offset that is included in the 918 piston design (meaning that are truly symmetrical).

Independant of the pistons, the other very worthwhile mod would be to install a scotch key on the IMS/primary drive.  This will safeguard any issues with the IMS bolt not having sufficient clamp force and the engine losing cam timing.

Who are you entrusting the engine build to?  He should also be a guiding force in determining what needs replacing once everything has been inspected.

 

  • Like 1

1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

Link to comment
Share on other sites

The rebuild is due to the oil pickup breaking off causing oil starvation.  Full Rebuild, Gator motorsports in Indianapolis Indiana is doing the work, they have rebuild many V8 engines including the owners (he races his a bit).  They have done stock to not so stock rebuilds.  

He (Owen) plans to let me know more when he has it torn down, and I have asked about upgrades that may be needed.  He said the only real upgrade is the pistons and that will be up to me since it is a stock rebuild.  Of course if I ever did decide to add more having it done would be added value.  

Having owned an all out performance car prior to my Lotus, I had a Cobra Replica with an SVO 460 with 550 wheel horses and zero safety items in the car.  I have no issues with how the lotus performs as a fun weekend car or even cross country trip vehicle.  I have no intentions of dropping to 3rd gear at 70 MPH on the interstate to just spin tires, I had enough of that in the Cobra.  I want to enjoy my dream car and just drive it.

Link to comment
Share on other sites

Sounds like everything is very much in the right hands.  Fingers crossed that your crank can be reclaimed after your oil pressure failure.

I would agree with your Workshop that for stock power there is really nothing that needs to be addressed apart from the IMS safeguard.

Hope you are back on the road soon.

1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

Link to comment
Share on other sites

21 hours ago, MD355 said:

Joey, do you have a pic of the broken pick up pipe.

Did the mesh end fall off the pipe or did the pipe break where its brazed to the flange that bolts it to the pump/front cover.

Thanks

alan

 

21 hours ago, MD355 said:

@Joey4420 when my Oil Pressure Release Valve (PRV) failed and my engine suffered from oil starvation causing a spun conrod bearing, I had to dismantle and rebuild the engine.

I had to replace a lot of parts, including new oil pump, head bolts and head gaskets, which are not cheap.. Furthermore, the labor was going to be expensive.. So I decided I had my one and only chance to upgrade the cast pistons with CP Carillo forged items.. The price was right, and I decided to go ahead and do so..

My crankshaft was repaired and rebalanced based on the new pistons, and I am very happy now to know that my car has forged internals (the conrods are already forged steel, so is the crankshaft forged steel)...

So, even though I work with stock turbo pressure (I rebuilt the turbos, fitted K&N air filters, deleted cats and muffler - just straight pipes, and put Sport 350 ECU) I am very happy to know that my car now has much stronger internals than when it left the factory..

Just think that you get your one chance to put those pistons..

Of course you decide, but this is my opinion..

Makis. can i ask what failed on the oil pressure relif valve, stuck open/closed, spring broke ? and what can you do to the new one to overcome the problem?

Ta

alan

Edited by alanlambert
edit
Link to comment
Share on other sites

7 hours ago, mike_sekinger said:

there is really nothing that needs to be addressed apart from the IMS safeguard.

Mike, Have you heard of many IMS bearing failures?

Being an ex Boxster driver I was always wary of their reputation for causing complete engine failure.  🥺

Cheers,

John W

http://jonwatkins.co.uk

Link to comment
Share on other sites

1 hour ago, alanlambert said:

Thanks Joey.

If the pipe came off the mesh filter wouldnt it have still been immersed in oil though ?

yeah but the loose parts make contact with spinning couterweights, my crank still has the shaving marks. 

Link to comment
Share on other sites

2 hours ago, alanlambert said:

Joey, do you have a pic of the broken pick up pipe.

Did the mesh end fall off the pipe or did the pipe break where its brazed to the flange that bolts it to the pump/front cover.

Thanks

alan

 

Makis. can i ask what failed on the oil pressure relif valve, stuck open/closed, spring broke ? and what can you do to the new one to overcome the problem?

Ta

alan

Based on my mechanic, we found the PRV stuck open..

Fortunately this happened at low rpm. Immediately I saw the oil pressure light come on and slowed down, but it was too late.. I knew something was wrong, the metallic noise, so I towed my car to my mechanic where immediately he diagnosed a failed conrod bearing.. The bearing that failed was the one further away from the oil pump.. My mechanic said it would have been worse if a piston had seized..

The verdict was that the previous owner had not changed oil regularly and as a result the PRV accumulated dirt and got stuck open.

Of course we replaced the PRV with a new one, and I also installed an oil pressure gauge, since the 2001 cockpit only has water temp..

Link to comment
Share on other sites

1 hour ago, jonwat said:

Lost me there I'm afraid 😨 

if you look closer at the pic, the pipe broken off the screen, the bolts snapped off and the screen with the mounting tubes was just flopping around.

  • Like 1
Link to comment
Share on other sites

11 hours ago, jonwat said:

Mike, Have you heard of many IMS bearing failures?

Being an ex Boxster driver I was always wary of their reputation for causing complete engine failure.  🥺

The bearing spec was changed quite early on.  As I understand it, the majority of the failures were due to insufficient torquing of the IMS bolt.

  • Like 2

1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

Link to comment
Share on other sites

I opted for the stock re-assembly of my 918 when I rebuilt it.  re-used the pistions and liners, even reused the piston rings  along with oil pump. Only replaced main/rod bearings, I honed the cylinders with a 280grit ball hone and they came out beautifully.   My compression numbers where erratic before the rebuild but after the rebuild, on a cold UN-started engine I was already back to normal balanced compression numbers. withing 5psi of each other. I was ultimately more concerned with oil pressures, oil clearances, clean oil passages throughout the entire engine, every oil galley was uncovered and flushed out. Ran new oil cooler lines and oil cooler, twin oil filters and uncovered the baffles on the valve covers to clean out the crud that you cannot see. 

I somehow ended up with higher then normal oil pressure with a VDO mechanical oil pressure gauge. But I also hand polished my camshaft journals .  

  • Like 1
Link to comment
Share on other sites

  • 2 weeks later...
7 minutes ago, 99ESPRIT said:

Just curious what were your compression numbers before and after the rebuild?

If this was for me, sadly I have no idea what they were before.  Rebuild should be starting soon.  In queue at the shop.

Link to comment
Share on other sites

10 hours ago, 99ESPRIT said:

Just curious what were your compression numbers before and after the rebuild?

I do have them. But on a short vacation currently. I did a mild blueprint of the engine writing down as much as I could measure. I’ll get back to you end of the week. 

Link to comment
Share on other sites

On 28/03/2021 at 14:56, v8GTmac1 said:

I do have them. But on a short vacation currently. I did a mild blueprint of the engine writing down as much as I could measure. I’ll get back to you end of the week. 

thank you!  i`m doing a rebuild and would like to see what your compression was after when your pick up tube broke?  thank you for getting back to me.  Kent

Link to comment
Share on other sites

On 02/04/2021 at 17:35, 99ESPRIT said:

thank you!  i`m doing a rebuild and would like to see what your compression was after when your pick up tube broke?  thank you for getting back to me.  Kent

 

here you go, Yes this was after the Pick up tube broke. Your numbers will be at a different scale due to elevation differences where we live, but you get the idea. 5 Revolutions for each to measure the actual balance between cylinders and then full compression from each. DO this on a fully charged battery with all the plugs out and Main fuel pump relay out and WOT.spacer.png

 

and here is a poor picture of the repaired tube, mounted to a 1/8" alloy plate during the repair. There was mulitiple repairs made, maybe you can see the weld line on the near the 2 bolt flange, that is an added 2" section of pipe, I also bought 2 new tube stands with new bolts From here Steel tubes spacer.png

Truth be told, In order for me to repair this mangled mess, after mounting the new tubes and new section of pipe was acquired, I had to mount it all while on the engine stand, add layers of cardboard,cloth,plastic bags to keep debree from entering the block, and tack weld it all in place. THen have it finish welded with a TIG.

Edited by v8GTmac1
  • Like 1
Link to comment
Share on other sites

1 hour ago, v8GTmac1 said:

 

here you go, Yes this was after the Pick up tube broke. Your numbers will be at a different scale due to elevation differences where we live, but you get the idea. 5 Revolutions for each to measure the actual balance between cylinders and then full compression from each. DO this on a fully charged battery with all the plugs out and Main fuel pump relay out and WOT.spacer.png

 

and here is a poor picture of the repaired tube, mounted to a 1/8" alloy plate during the repair. There was mulitiple repairs made, maybe you can see the weld line on the near the 2 bolt flange, that is an added 2" section of pipe, I also bought 2 new tube stands with new bolts From here Steel tubes spacer.png

Truth be told, In order for me to repair this mangled mess, after mounting the new tubes and new section of pipe was acquired, I had to mount it all while on the engine stand, add layers of cardboard,cloth,plastic bags to keep debree from entering the block, and tack weld it all in place. THen have it finish welded with a TIG.

did you have to put in new rod and main Bearings? if so where did you purchase them?  i did read that i believe your pistons were ok and you just re ringed the old pistons and honed the liners? where did you purchase your rings? did you do the rebuild yourself?  sorry about all the questions   Kent

Link to comment
Share on other sites

2 hours ago, 99ESPRIT said:

did you have to put in new rod and main Bearings? if so where did you purchase them?  i did read that i believe your pistons were ok and you just re ringed the old pistons and honed the liners? where did you purchase your rings?

did you do the rebuild yourself?  sorry about all the questions   Kent

new rod and mains Yes from Jaeparts,  idk where you are located but these guys are in California.

Pistons did not have any damage and the rings looked good up close visually I guess you have to look at them up really close and look for pitting.  I did do all the work myself and purchased this exact ball flex hone. I tried to buy rings for the top but they had to be custom made. Just re-used them with 42k miles on them. 

 

BUt keep in mind when doing all that work, you have to press out the cylinder liners and reseal them. I ordered the tool from a UK Lotus vendor, then I ordered the liner sealant from JaeParts.  It took me 1.5 years from start to finish. Parts sourcing, machine shop re-work of the crank and head surface, and buying tools I didnt have. 

It was a lot of work for which I was quoted $25k in California.

Edited by v8GTmac1
  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...