V-12 Engine into 308 Build, over on Grassroots

Ok, sorry for the delay.
Could not find any models. I had put together files with the 2d sheets as a background layer, that's as far as it got. I've got our coil overs but obviously can't share that, wouldn't help with what your after in any case.
I wonder if anyone on grabcad has something.. Probably not.

This where 3D scanning comes in real handy. The new iPhones do that, got one of those?

 

Thanks for looking.

iphone? Seriously? you know I'm and engineer right?.....and I like to believe I have at least some self respect

I mean "no I don't"

 

Forgot to add this. I'd never ever hear of tire spring rate but came across while reading. I knew they flex and different tires ride different but I never really thought about including that in the spring rate calculations and don't recall seeing it motion ratio or spring sizing formulas. I guess on most street cars the tire is stiff enough that it can be ignored without creating a lot of error, but as spring rates climb, the tire rate starts to matter and is somewhere around 1500lb/in and in the rear of my car is about 1/3 total travel the way I currently have it sprung which seems too big to ignore.

 

I'm an ME too, and converting tire pressure to spring rate... Yikes!! I've read some articles on making cars handle where the tire pressure / spring rate relationship is mentioned. I always figured that was sorted out at the track (other compliant elements at play like the chassis etc.).

 

Your project is incredible.. The sound is just terrific!!

 

"The brake pads never arrived. The Last week I called/emailed a couple times and they sent a refund saying there was a production issue and it will be 10-12 weeks before the pads are available and they will email to let me know. They were the cheapest place and since the car doesn't run I've not tried ordering elsewhere. This is how the whole project goes though, even the simple stuff take way more time than it should."

And this is what I admire most when building a car: To keep pushing past that nonsense. I once re-designed a hub from 5-pin to 6-pin because I was promised 6-pin (knock-off) wheels. Only to learn once I was ready that they need an order for 20 sets before they start casting.

Now let go back to page 2. I only saw your threads (this and the V12) an hour ago.

 

I guess it's a measured thing more than math. The plan is that when the wheel scales are set up I will jack the wheel to just touching and measure scale to wheel, then drop it to about 100lb, remeasure, repeat until the the jack is out and maybe add some weights to get a decent curve. Hopefully 10-15 minutes per corner and hopefully still close enough when new tire day arrives.

Then the frame. I posted this before


On a GTS, a 1g single corner bump will move the wheel about 0.5"...it might be a bit less as I'm not certain I did the math right. But worst case, 0.5". With the springs I have, the travel will be about 1.5", the the tire another 0.5"? (we'll find out when I have the scales).

I think this all means that I have control of not quite 2/3 (1.5/2.5) of what is going on. But normal cornering it's more like 3/4 and I still what to make the best of it either way. I have about 1/4 the wheel travel as stock so I have some suspension geometry options the factory really didn't, things like camber gain causes track width variations that bind the suspension and cause tire slip..but less travel means I get less track change and that means I should be able to bake in more camber gain. Well see what it all looks like once I find time to build the CAD model.

 

I just pulled up my braking weight transfer spread sheet. Eye balling between that and my suspension calcs, the nose drops 2 or maybe 3in going full throttle to full braking. I'll get the math onto the suspension sheet so the numbers are real, but that it a pretty big change for a car sitting 4in off the ground and why I'm feeling like the drive/shut needs to be addressed.

 

Very nice! I watched your video.

Do you think you'll use your car at club sporting events? With all of that amazing horsepower, it would be fun to see Rxn's of other club members with 308's. You could have fun 'lines' at the ready, like, "She runs pretty strong", "I found this great new spark plug!" Or, "I use brand xyz gasoline".

Oh.... and by the way, I put in a well tuned Ferrari V-12.


When I ran club Hillclimb events with my GTS (like 30 years ago), the big thing to get up the mountain quickly was tires. The Yokohama A-008RS and Goodyear GSCS were the rage. They stuck like glue, but sure didn't last very long.

 

Yeah, I don't know, the previous owner was on about it being a limited edition and it's always seemed pretty quick......

The plan is get back to some autoX fun. Yokohama is still fast, A052 now andvtge Bridgestone re71rs seem to be the best of the 200tw street tires. Both like quite a lot of camber they say which is what has me a little obsessed with camber gain geometry at the moment thinking to get it handling on the course but not destroying the inner edge of the tires on the street. Might be wishful thinking....

But I do want to address the front dive, that I know I can improve.

 

This guy has a bunch of good suspension videos, this one on lowering a car is maybe worth a watch....basically he says it makes a hot mess out of the suspension

 

Some measuring and CAD time tonight and I think I have the geometry roughed in pretty well...and I guess unsurprisingly the roll centers are quite low with the front basically on the ground. also of not maybe is the wide tires I put on the back mean the rear track is now narrower than the front be quite a bit. I still need to do the side model but that should be quick now.

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This suspension model is in onshape:
https://cad.onshape.com/documents/b011a99c2d071b602b38db26/w/82103bb60a91a1e0f3b4c900/e/39a7c735b9b3b760b680179c?renderMode=0&uiState=6644a820c569b84e1f9a91eb

https://cad.onshape.com/documents/b011a99c2d071b602b38db26/w/82103bb60a91a1e0f3b4c900/e/646bad00017359fec0d85cfb?renderMode=0&uiState=6644aa4ac569b84e1f9aaa58

its free to use, you just need an email to register...not share if you can view without registering but if you are registered you should be able to make a copy to play with. I will clean it up a bit so ride height, tire width and wheel offset are easy to change without buggering anything else.

 

Super cool Mark, thank you!

 

Hi all - I posted this to @mk e in another thread but he asked me to bring it over here. The topic is on nose dive in the 308 and front suspension setup.:

One approach to address this is through the suspension - I was looking at some coil-overs that supposedly have some anti-dive magic built in by Intrax.

The 1988.5 328's came with a different front end geometry that promoted anti-dive characteristics - this was derived more in the 288 / F40 and Mondial. They changed the mounting points, angles and a-arms to accomplish this.


Here are a couple useful old threads to piece it all together:
https://www.ferrarichat.com/forum/threads/308-328-gtb-chassis-diagram.405266/ - this is both chassis diagrams of the pre / post '88 328 front geometry changes to address nose dive.
https://www.ferrarichat.com/forum/threads/has-anyone-ever-built-custom-a-arms-for-the-308.346778/ - has some discussion on the geometry changes.
https://www.ferrarichat.com/forum/threads/328-experts-factory-suspension-upgrade.159363/ - this one looks at the parts between the early and later 328 front setup.

In the third thread of these it mentions lower pickup forks - interesting if you look at the parts on superformance - https://www.superformance.co.uk/328/suspension.html

Cheers,
Spencer

 

This is the geometry approach. Now this is addressed computer intervention in systems like Porsche PASM, magneride, and some aftermarket solutions like DSC https://www.dscsport.com/product/stand-alone-kit/

 

He gets a C I think. ....I don't think anything thing was wrong but it's incomplete enough to be misleading. Jacking is THE concern as you add additional lifting force.

If the rear has anti-squat it, it becomes pro-squat or anti jacking under braking which helps offset the front some.

That is what I need to play with I guess.

 

Im just taking a page out of the group 4 builds on my car and Im sure that'll be good enough for me. Other than the coil-overs and bars they worked with what the factory provided. I imagine the rule book had a lot to do with that but it also shows you can make one handle without getting crazy.

 

This was my first idea and for the rear it seems a no Brainerd. Up front I a bit worried about what it would do to bump steer. For sure worth looking at though.

 

Always so rational.....but im not giving up on you because i believe in my heart that one of these days I'm going to talk you into doing something stupid

 

Oh looky what I found, 1976 308GTB group4 drawings

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This is a really cool find. Any idea what the outright differences are between the Gr. 4 stuff and normal road cars is? Apologies if it's been covered elsewhere, prior.

I haven't peeped your thread in a while, but I just saw your burnout clips, this car looks like a HANDFULL! Sounds bitchin, and looks like a rocket. Are most of the suspension changes you are seeking focused on retaining traction?
Also, weird question (forgive my ignorance) but with the increase in power and potential increase in traction, are you or have you done anything about the potential weak point on the factory outputs on the axles?

 

I'm playing with those drawings right now (and kind of broke my CAD model a little, I typed a number or constraint wrong somewhere) and I don't see any difference from the street car. I know they are homologated so rules might not allow much. I know the race cars weight in at right about 950kg (2100lb) which I think was the class min, light weight everything but the suspension sure looks like factory pieces.

Handful is a good description. I don't think the wheel hp is much if any over your low boost 640 number but it sure seems to make a lot of torque everywhere. I haven't had it running long enough at any one time to make it to a dyno...maybe in the fall if the new head gaskets arrive and I have time. The simulator says this (crank numbers)
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5.4 liter is a big engine, it just makes torque. I'm guessing this is a very different shaped torque curve from you 2.0/2.4 turbos thought the peak number is probably similar?

Part, maybe a big part, of my traction issues are the old tires. I'm pretty cheap and don't want to buy new until I know the engine is running and I actually need them. 1/2 picking up on stuff I was working on with the last engine (factory 3.0 V8 with about 24psi blower setup, like500hp/420ftlb at the crank, blower motors make a lot of torque everywhere too). Back then the tires were new but hooking the back end wasn't any better. I don't think the squat is causing the traction issues, it just kind of annoys me along with the nose up/down throttle to brake. For sure I could just be smoother, but I'm equally sure the car could behave better and just kind of want it to be about as good as it can be before I adapt my driving to better suit it. I have an old autoX video, very low quality, but if you skip to about 45Sec and freeze it you can see the roll I had with the old 400/250 spring setup and and watch the nose full throttle to full brake which has gotten worse with the new engine. Just trying to ship away at the handling stuff I don't like.


Yeah, the stub axles......they are going to break. Its not hp the breaks them the best I can tell, its cornering time on sticky tires. they break where the wheel flange meets the shaft at the outer bearing. I have a vague plan to up-size the outer bearing and machine new shafts but they aren't broke yet and other things are so it remains a vague future plan. I guess before they break I could try up-size the bearing, weld up the shaft and reheat treat it which would be easier than making new, but still not broke yet......

 

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This is the only graph photo I've got saved on my phone. Torque curve starts way wimpier but climbs and is very peaky. You can also see why I am very eager to swap out this monstrous turbo for something significantly smaller (I've got a Garrett G30-770 on the workbench ready to go in) and that should make the entire powerband way more usable and smoother. Honestly, the above is a pretty ugly dyno graph, but once you're in the power, you stay in the power.

Honestly, yeah it sounds like tires will play a massive role in the way the car drives. You might surprise yourself! I can appreciate wanting to smooth the car out as much as possible before learning to drive around it. The video clip you showed seems like the car has a remarkable amount of dive to it, so I understand the plight. Honestly I'm surprised it has so much.

 

Yup, looks like a huge turbo curve! But as you say, its a track car so there is no reason in the world to ever be out of the boost region. turbos and road racing are a match made in heaven in that regard. A wider boost curve will likely make mistakes less expensive lap time wise but out on the track hp is hp. Just stay above the torque peak because as you roll the throttle in and accelerate out of a turn a dropping torque curve you need to keep adding throttle to keep accelerating. A rising torque curve and well you have my burn out video where as soon as traction is broke the engine rpm wants to jump nearly instantly up to the torque peak. Years ago I raced a Kawasaki 600 bike that came from the factory with a dip in torque, between 9000 and 9500, then it rose to just over 10k, peak hp at 12500, redline at 14k. If I missed a shift into the turn and got below 10k bad things happened where I'd be rolling in the throttle and by the time I knew the rear was moving out the rear was moving out FAST and it was in high-side territory before I could react and at that point reacting was as dangerous as hoping for the best. But you have a nice curve as far as that goes. Race it!

Oh, I'm sure you're right. They are old and it was a cold day and even new they didn't like road temps below about 60F. It's just taken so long to get things on the engine sorted I don't want new tires to time out while I **** around with the stupid the engine, I just don't have the budget to buy expensive parts stuff twice when I can avoid it. 308 suspension has no anti dive or squat of any kind.....you have springs and dampers and the dampers just delay where the car will settle. I don't know where you are spring frequency wise, but in that autoX video the 400/250 springs yield about 1.75hz which is supposed to be right where sports cars should be...1.5-2.0hz. My current springs, the ones you can see bouncing in the burnout video are at 2.4hz, well into the the race car range and about as stiff as they recommend for anything not running aero.

My shock damping rates are on the low side, compression in particular and having another look at that is after geometry on the to-do list. I like the lowish damping rates on the street because it rides nice, but its probably time to learn to like a firmer ride. Also is the engine itself, the hp is one thing but then throttle off on a big high compression engine and there is a lot of compression braking going on. No shortage of items to wonder about.....