2.8 Stroker rebuild - s2 bronzit coupe

[ryan12590]

Hi all,

Been lurking/learning/accumulating parts around the forum for long enough and recently began rebuilding my b25 swapped e30.

The plan: M20b25 (1989 - e34), M52b28tu 84mm 328i crank, 130mm 320i (heavy af) rods, b25 stock pistons.

- Crank spacer machined and fitted to crank snout
- Piston skirts trimmed flush
- Crank weights turned down and trigger wheel removed

While the engine was apart there's also a long list of other mods being added along the way:

- RHD flywheel 228mm
- Bimmerheads reground 284 degree/435" lift cam
- ECUMaster DET3 piggyback with a Sssquid chip tune
- AFM delete
- 19lb Pink top injectors
- Most engine parts and ancillaries vapour blasted or plated, and rebuilt

Meanwhile, I have also taken on shaving and smoothing majority of the bay, although thats for another project thread.

Questions :

1. I plan to run the the engine for break-in on the stock motronic ecu with the sssquid chip suited for a 2.5ltr displacement and the AFM still fitted, will the engine compensate enough fuel for the increased 2.8ltr capacity by way of O2 sensor and AFM? Anything I need to be mindful of?

2. Any suggestion in regards to either lashcaps or oversized eccentrics to suit the lower base circle on the reground bimmerheads cam? I have CAD designed larger eccentrics and could do the same for lash caps, whats the suggested route here?

3. Using stock springs and rockers, they are both in near new condition and rockers were inspected for porosity and bad castings, all clear. Am I pushing the limits not moving up to beehive springs or HD rockers, how high is the risk?

On to the pics :coolphoto: :

[ryan12590]

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Crank Spacer, machined using schematic from e30zone, made a batch of 5 and on sold the remainder

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Some funky headers the engine had already fitted, these are at the exhaust shop having a 3 inch V-band added to the collector and being thermal coated in white.. should be interesting, been about 3 months Ive been waiting to hear about these.

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B25 stock pistons, low comp version 8.8:1, as you can see the skirt has been removed down the the internal casting, about 5-7mm from memory. This was a requirement with the oversized counterweights on the m52 crank also pictured, mainly because i ended up with a late model 328i crank, also had to reduce the radius of the counterweights by approx 8mm on the largest counterweights, most of the machining was done by trialling and removing material until there were no clearance issues.

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Midway through the head being rebuilt, the original head was discovered to have a crack through the water jacket into the combustion chamber. Another 885 head was sourced...and also discovered to have an even worse crack pictured above.

[ryan12590]

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Pic of the e30, back before she headed into the garage, hasn't left in 18 month! Wheels have also been swapped for a set of 16x8 et0 7twenty wheels.

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The dreaded intermediate shaft, pulled this as the block was hot tanked and didnt want to risk the bearings being ruined, bearings have been ordered and are one of the last parts to arrive and be fitted, planning to use an expansion plug technique to fit them and then use a brake cylinder hone to bring down to the correct tolerances.

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Goodies pic, the VR gasket kit I now regret, and have since ordered a Goetez HG replacement.

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Sketched up these eccentrics, they are 2mm oversized, 18mm compared with 16mm stock, not sure to go ahead with these, or go lash caps.

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Lastly the DET3 unit, planning to use this for some adjustments to the tune to pickup where the the Sssquid chip falls down and to eliminate the AFM hopefully too, no exp tuning so that shall be fun.

[sampayne]

Looks like you are well on your way. Are you going to get the used rockers re-surfaced? It's not common, but I have heard of people doing it. Otherwise, I would get new rockers. It would be a bummer to wipe a cam on a nice build like this because of used rockers. When buying rockers, it's only about $100-$150 more to upgrade to HD rockers, worth it in my opinion for the piece of mind.

[digger]

The HD rockers are slighty different geometry to work with regrind cams if I recall. Alternative is to buy oversized eccentrics

[ryan12590]

Looks like you are well on your way. Are you going to get the used rockers re-surfaced? It's not common, but I have heard of people doing it. Otherwise, I would get new rockers. It would be a bummer to wipe a cam on a nice build like this because of used rockers. When buying rockers, it's only about $100-$150 more to upgrade to HD rockers, worth it in my opinion for the piece of mind.

Not planning to resurface the rockers (didnt know it was an optiong tbh!), was hoping they were in good enough shape to run as is without problems.

Although there will be increase load on the rockers and springs..hmm

Problem I'm finding as of late is currency conversion into AUD$ from USD is terrible at only like 71 cents for every USD. meaning HD rockers are around $500 AUD delivered at the moment!

Trying to keep costs down for the rest of the build, blew the budget with extra machining and replacement head which attract a premium in Aus.

[ryan12590]

The HD rockers are slighty different geometry to work with regrind cams if I recall. Alternative is to buy oversized eccentrics

Tried to find out some more information on this Digger and ended up on another of your threads



I have a fair amount of gap between the stock eccentrics and the valve, may need additional adjustment even if the rockers are suited for reground cams.

Thinking I may stick with oversized eccentrics as lash caps don't feel like the right solution to the problem.

Thanks for the heads up, btw your stroker posts definitely inspired this build!

[ryan12590]

Guys, the head and block have been skimmed 0.5mm from the stock stack height, assuming a stock HG and 284/11.05mm lift, piston valve reliefs have not been touched.

Before I get too deep into reassembly, whats the likelihood of running into piston valve clearance issues? Should I have the reliefs enlarged/deepened?

Also any information on how to convert the engine to a non-interference similar to Metric Mechanics, is it just oversized reliefs? Assuming there isn't enough meat on the 8.8 pistons to allow for this?

[e30davie]

First photo - i saw the table you have all your parts on. Thought, hey i know that table, that' a bunnings table! checked your location and yep Brisbane Australia. haha. hello fellow Brisbaneite!

great project, cool lookin car so far:)

[digger]

there is about an extra 1mm of the clearance taken up by the looks of it.

i would have pockets atleast deepened and perhaps +1 on inlet to allow bigger cam and better head later on though yours would probably be ok as is with current cam and stock valves.

set the piston to head to 1.0mm +/-0.1mm to get the correct deck height. IMO do a quick mock up of 1 and 6 with bare head and old gasket.

i wouldnt worry about making it non interefence its unlikely you could on stock pistons and it compromises the combustion chamber. Really just use good parts and adhere to the relevant maintenance intervals and you shouldnt have any issues if you check the piston to valve clearance.

[sampayne]

Problem I'm finding as of late is currency conversion into AUD$ from USD is terrible at only like 71 cents for every USD. meaning HD rockers are around $500 AUD delivered at the moment!

Trying to keep costs down for the rest of the build, blew the budget with extra machining and replacement head which attract a premium in Aus.

Ah understandable.

Might be worth an inquiry at your machine shop to see if they can be resurfaced. Heres a video I found. It's potato quality, but you get the idea.

https://www.youtube.com/watch?v=k5CV3pv1Bgo

[hasa]

Did you balance the crank after cutting the counterweights ?

[ryan12590]

Back from the dead!

Managed to button up the engine and confirm clearances were all satisfactory, its now partly dressed and ready to go back into its home.

Working on the exhaust headers which became slightly warped after ceramic coating, due to the individual header flanges allowing movement.

Considering swapping to a Gates Racing timing belt, while its still out of the bay, still undecided.

Engine has been sitting on its stand for way to long now waiting for engine bay to be brought up to scratch. Rust repairs suck!

[ryan12590]

Did you balance the crank after cutting the counterweights ?

Sure did!