V-12 Engine into 308 Build, over on Grassroots

More painting. These parts should be yellow zinc plated but I don't have time for that right now and this really ain't that kind of build.

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I had stainless spacers made up by extsw.com to reduce the need for many shims. I know you do your own lathe work, but I don't have a lathe, and the folks at exist do decent work fast and at very reasonable prices, so a reference for others.

 

How much camber are you running?

 

-1.5 in the rear, and -.5 at the moment in the front. I will be running a bit more in the front once I install longer bolts in the front pivot forks.

 

What tires are you running? And have you pushed it hard anywhere (track or autoX) or just street? I think around 3 degrees for the A052 tires I have....I think.....

 

Factory size Michelin XWX. It is just be a street car. I have other machines for the track, not that I do much of that these days.

 

That's for sharing the info!

 

Gawd, I hear that....it's why I'm selling my track cars and planning to modify the 308 to run the few track days I seem to have time for any more.
- Dave

 

It warms my heart to hear about a 308 being made ready to be driven angry

What are the prep plans?

 

Home again home again jiggity jig
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I know it fits, I know how to angle it, but every time the stress stress of seeing it.......I do kind of wish an engine compressor was a real thing
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Last time one of the alternator mount bolts let go so that got a helicoil
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Tomorrow I'll try to get the front headers on....they are a bugger and again the engine has to be in just the right place.

 

EVERY time I see your in/out pics, I think what your teachers probably thought back in school: "It's not supposed to work that way, but he did it anyway.... again"
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Thanks for being another one of "those guys" who make life interesting.

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Carry on!!

 

Nothing too exciting Mark. It will still be a road car primarily - not a track rat - so aside from basic suspension and brake upgrades to start, the biggest part of the project will be to see how much weight I can strip out of the thing without resorting to 'glass body panels and titanium everything...along with resolving the inevitable issues that the track days surface of course. Should be fun.
- Dave

 

I need to pick up the pace....the ECU boards are in production so not a lot of time left before I am the hold up

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Tonight I set a new personal best for installing the front headers and getting the engine sitting on its mounts...45 minutes! I was using the engine hoist to hold the engine up so I could reach the header nuts, but this time I used a jack so the hoist was out of the way...so much easier! Than mounts bolted, water pump, alternator and oil return pump all on. Vodka time

 

@mk e I am getting caught up from February. I saw the spherical bearings on chassis mount end of the a-arms. I am curious to the ride quality post road test. I am also selfishly thinking about myself and my own project and how any toe and the poly bushings binding I plan on using. It definitely makes the case for more modern tubular a-arms that have the toe adjustment built in to the arm side of the mount.

per the lower roll center - very cool. I always thought of making new suspension a-arm mounting forks with multiple holes (and new upper chassis mounts), and upper shock mount holes with multiple holes so the entire setup could go up and down and maintain geometry. At the same time, getting a stiffer anti sway bar would reduce roll - those new blade adjustable ones are pretty trick. I do like your approach working around this!

 

@sltillim - it will still be a bit before any test drive, April sometime is my guess. So far I think the suspension has been going in the right direction, the past changes have improved things and hopefully this round of changes will about finish it. I want to see where the body roll and f/r balance are before thinking too much about sway bars...but I do have my eye on something like these:

https://1speedway.com/index.php?route=product/product&path=76&product_id=90
https://1speedway.com/index.php?route=product/product&path=76&product_id=88

But right now a ton of stuff to get finished....hook up the engine, wire in the the ECU, assemble the rear suspension, The front suspension needs the same treatment as the rear and the power steering is still broken. Then tune the new ecu and drive the car a bit, I'm hoping to get it to an autoX so I can really test the suspension changes...on the street you get ride quality and maybe how responsive the steering feels, but until you go out and slide it a bit its hard to know what you actually have. I see a bunch of spring combinations being used that I just don't think should work very well, I'm not really sure why the stock springs were chosen so maybe I'm missing something....but the stuff I've tried oven the years has been steadily making it faster so I think I'm on the right path....think.....

 

Totally tubular sway bars!!!! YES!!!! I got stuck on the ones used on the stanceworks build that incorporate that style bar:

https://www.elephantracing.com/porsche/914/swaybars-for-914/blade-style-swaybar/
https://tarett.com/collections/swaybars-drop-links-911/products/bladed-swaybar-drop-link-kit-front-65-89-911-912-930-914-911fbldsba

Look through their different bars for the different porsche models - some very interesting setups for adjustability.

Do we know the sway bar rate (torsional spring rate) of our 308's? I have looked it up but never found a number. Plus there were the two thickness of the gtb and gts. I am not sure of the differences between front and rear. See, I am good at questions. Answers? That's a different story.

I want to be able to do some autox when I'm done. PCA does a lot of that around here. Your spring weights seem very heavy, granted you have a heavier lump. Its the age old argument - of ultimate spring / sway bar setup.

I feel like everyone else get's 10x more done in less time. I'm realizing its been nearly 3/4 of a year since I decided to buy my motor and I am almost ready to pull the old one out. So much planning, so many parts to buy, so many decisions! I have to post some updates. Your progress is always inspiration!!!!

 

Blades are nice for quick small track adjustments....most people will never be making that sort of fine adjustment

My GTS came with 18mm bars front and rear. I made a spread sheet to compare different option, the J term is the relative torsional stiffness
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Currently I only run the front bar, the rear came off as part of the big wheels and I had a rear grip issue anyway so it was better without it. There used to be 1", 7/8. 3/4 options available for 308s and the popular combos were 1+7/8 or 7/8+3/4. I am generally not a fan of huge bars, they make the suspension less compliant in 1 wheel bump, you know, like say running on to the inner curbing mid corner. On the street they aren't too bad as most stuff is 2 wheel bump and they allow good roll control with softer springs. What I am doing is rising the roll centers so the car is inherently less prone to roll and using pretty stiff spring so very little help from swaybars is needed. The softer the springs and lower the roll centers, the more bar you'll need. My plan is just use them to fine tune a bit. Lots of ways to get their in the end.

Springs....the stock spring rates are too soft to be considered sports car spring, touring car. also the rear springs are stiffer than the front, that was a thing to let the rear bouncing catch up to the front after a bump on the highway......before shocks really worked but it continued in designs I thing as an "every one know you need to XXXX' kind of thing. So just a bit weird setup for a sports car by modern standards. Spring frequency is how springs are compared and stock is 1.2/1.4hz. Mine are 2.4/2.2hz so up at the stiff end which tends to work well for autoX, high corner lows but lower speeds. Something like 400/250 would be 1.7/1.6 and kind of the line between sports car and getting into race car - these are what I ran for a few years and they are pretty good feel pretty good generally but I like the responsiveness and body control with the new springs better.
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How it feels though is not just springs, its also a lot the damping rates so soft spring with stiff shocks or stiffer springs with softer shock will feel quite similar. Strret cars the standard is lowish compression to let the wheel move hitting a bump, then more rebound to prevent the springs from oscillating, about a 1:3 ratio. On a race car it will be a lot closer to 1:1 ratio and that is the knock your filling out feel. For general street speed driving I personally like more spring, less shock but that is personal preference.

No easy answers.

 

Interesting data point for Column E would have been "Weight"....especially for the 1.0" and 1.25" solid bars.
- Dave

 

sure, here is for a 34" long bar in lbs, not counting the ends

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Interesting...thanks Mark. So swap the stock bar for a thin wall 1.25" unit and increase stiffness 2x while cutting weight 1/3x. Any fatigue considerations with such thin-walled tubing? Seems like the twisting motion would be spread-out across enough material to maybe mitigate the issue?
- Dave

 

Torsional stiffness is a diameter to the 4th power relationship so vs weight which is dia tp the 2nd when you see stiff like that is just screams use a tube not a bar if weight is a concern. Steel is generally not very prone to fatigue, I grabbed this off wiki:
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It show that with alum it doesn't matter what load you pick there is a fatigue limit but not with steel, stay below 30kpsi and it will last forever. The number move as bit with different alloys but its pretty durable unless there is a defect of some kind to get a crack started.

It doesn't really matter that its a tube not a bar stress wise, if you twist is 1 degree and its 1.25" OD, the surface see exactly the same stress where its a bar or a tube. Where the difference come is it you apply a fixed load the tube will deflect more than the bar so it does see higher stress and this is more representative of what happens in a car's sway bars. In general we design to stay below 30ksi in normal use, and if you do if you look at the chart you can hit 10,000 potholes where the wheel move double the design limit before there is sway be failure....that's a lot of bent wheels before the bars are a worry

 

Just curious but what kind of cold cranking compression are you seeing with that engine Mark?

 

About 180psi

 

and what’s the bore and stroke of this monster again?