Hey race fans,
Sometime in the future I plan on running a 2.7 six over my four banger. Anyone have any idea about where my weight will be after the -6? I'm I looking at 50lbs? 100lbs? More??
I could drop some weight from the car still. Want to get that HP to weight just right!!
Theres a large group in NASA (ST4) I think I could fit into perfectly If I get the math correct.

I'm not a super hard core racer, but the back end of my car has never felt heavy with the mag 2.7 or the aluminum 3.2. It feels pretty well balanced around the turns. Oh... the power is awesome!

I have gotten loose on the track and the car kind of evenly pushes, I think I am a little lucky that my setup happened to be balanced well enough from the beginning. Make sure you get 225's+ on the rear, that helped a lot.

To answer your question directly I have never corner balanced my car but with a 2.7L I weighed in at about 2200lbs total.

Sounds like a fun car. I always wondered how someone can not be a hardcore racer? Once I went to the track I've been on that slipper slope ever since! Its a real problem!!!
Are you 2200lbs with driver? I can work with that math but not sure if I can loose all that weight.
2200lbs at an average 196HP is ST4.
My cars current weight is 2251lbs with driver, 1/4 of gas and cool shirt cooler full.
The class i'm in now is ST5.
2291lbs at an average 157HP. (Had to add 40lbs of ballast)

So knowing the weight difference between the a -4 and -6 setup will tell me how much HP i need to get.

175lbs +\- for a 2.0-2.7
200 +\- for a 3.0-3.2
225 - 3.6

I obviously was hoping for a lot less.
Thanks for the info.

The 6 is beefier than the 4 but even if you just add 50% to a 4 (250lbs) you are at 125. Then add the oil tank and lines and 5 more quarts of oil. 50% more induction etc and you’re there pretty quickly. I bet just the cam towers, something that a 4 doesn’t have, adds 25 lbs. Most of the time, guys figure on 200 for a small 6 and 250 for a big one. That gets you in the ballpark.

At least the weight is in the right place.

I always tell people its an additional 150lbs.
but I think with all of the accessories... tank, lines... these numbers are good too

Also, the early Sandcast 2.0 is heavy.. I moved to a 7R case to drop more weight and remain 2.0


The race shop I use out here... (specializes in 914's) His advice is that the 4 cylinders can be built faster and lighter until about 2.5L
then the 6's start to make more sense

I just saw a dyno printout for a 2.0 sandcast six that was making 272hp at the crank. He uses it in his ‘65 race car. He said the mag cases would not last for him. They are all too old.

That I would totally agree with
the machinist tried to talk me out of the switch
explained that the mag will not hold its shape and will need full machining, including line bore at each rebuild. (the sand cast is much stronger and needs thousands less in rebuild machining)

That is amazing HP for a 2.0
how did he do that?
still an actual 2.0?

Even with a lot of expensive machining, the problem is the mag is getting brittle and starts to come apart. Age is not kind. We have mag parts that should be worth thousands, like 911S oil consoles, minilite wheels and engine cases but they are too corroded to use. I'm sure part of it is condition dependent (east coast) but mag is so reactive and it will eventually age out before aluminum. Luckily, Catorce and guys like him are bringing new product to the game.

Still an actual 2.0 but for the guys who can afford to race '65-911's, its just money.

[/quote]
Still an actual 2.0 but for the guys who can afford to race '65-911's, its just money.
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Still pretty amazing
anything over 110hp/L is pretty amazing

220, 230 was about the ceiling from what I had heard
that is darn good output!

[quote name='brant' date='Sep 5 2018, 12:41 PM' post='2645743']
[/quote]
Still an actual 2.0 but for the guys who can afford to race '65-911's, its just money.
[/quote]


Still pretty amazing
anything over 110hp/L is pretty amazing

220, 230 was about the ceiling from what I had heard
that is darn good output!
[/quote]
Porsche was doing 220-230 back in the late 60's on their race prepared 67-69S.

So at 2450lbs I need to make 218HP average at the wheels
So at the flywheel thats around 255-260HP. If I take in account a 15% drop from flywheel to the wheels.
Think I'm asking to much from a mag case? Hell, I'm at 160HP (wheels) with my -4 mag engine now.

You are looking at a hot 3.0 or 3.2 for around $20-25K or a 3.6 for around $15K. The 3.6 will be the heaviest and need some more specialized conversion parts than the smaller motors but any engine around 250hp will need lots of cooling. You are also getting to the point where you will want/need a 915 trans since unlike the street, you wont be gentle.

I wouldn't even begin to build a 250+ hp engine on a mag case. The 2.0's I was referring to are built on sand cast alum cases.

Our 962 is built on an aluminum turbo 3.0 case. Close to 800hp on the dyno.

I just noticed you two were discussing HP output for a 2.0, not a 2.7. I'd think 40-50 HP per cylinder shouldn't be that far out of reach.

As far as cooling goes, I have a large oil cooler and a trans cooler already set-up. I'd have to check my notes but I believe we never went above 210 degrees in Fl at a 14hour race. The trans cooler is still untested.

A 915 trans is in my future too. I just need to get my dad to part with it!

WOW, there allot of talk about just building up an early aluminum case motor here! YOU should do a price check my friend...because most folks would HAVE to think quite extensively before they take out a second on their house to build an engine. They warned us about this very thing in SCCA School. The slope is long,and the grade is steep, And at the end is Bankruptcy...LOL

I am very happy to just participate!

MB

Yea, the cases sell for $7-8K but building a real race motor is $ multiples of a street motor. I'm betting the 2.0's that are completely built out are $75-100K and up. It's more if you don't know what you are doing since you will blow up a couple engines just realizing what you don't know. Guys like Peter Dawe know it all and are worth every penny.

Ive been riding this slope for quite a few years now. I have enough parts now to build three cars!!

How does one get off this train?

NO IDEA!!! Although I will say as I am aging I enjoy working on the cars less everyday...

2.4 7r case ..save weight and money all uodates done... except ( oil bypass mod $200 )


or I have plenty of sandcast cases lmk machined or not bring $$$$$

Did you forget a zero?

(oil bypass mod $200) oops

Just wait until you decide to jump to a 3.2 liter 6 with 360 crank hp...then lets discuss exponential $$$....

though theres a guy that runs PCA and HSR racing in his early 2.0 911...has 3 engines: A, B, C. He uses the 'C' engine for PCA since its the most mild and he has no competition in his class. The "A" engine is for HSR/SVRA 2.0 racing. it pushes 260+ hp but needs to be rebuilt each year. "B" is back up in case the rebuild requirement comes earlier than expected... :-)

Said each engine was +/- $75k....

Kermee has a Peter Dawe 2.7 showing 215rwhp on Mustang Dyno. The car weighs 1945# with 1/3 tank fuel. The car is faster than the driver.
Engine rebuild costs over $30k.
Buttercup has a 2316 Raby kit engine showing 160rwhp on DynoDynamics. The car probably weighs about 2200. Rebuilt by myself 3 times in 2 years doing DE events at about $3k per rebuild.
Best bang for the buck would be a big /4 with dry sump & lighten the car.

Recently, while waiting through an 8 hour layover at the airport, I decided to (on paper) see how much weight I could remove from my early 914-4. I came up with 305 lbs. That's removing everything that doesn't make the car go or stop. Fiberglass hoods, lids, and bumpers, no side windows, targa top, trim, wiper, hood locks, ect. and making up some light weight brackets for the seats. If the car weighs 2000, that is a 15% weight reduction and should make the original 1.7 feel peppy, braking should shorten and handling should improve as well. A stronger 4 would really get it moving without having to resort to a high dollar build.
All mods would be easily reversible so I might move forward on this soon.

I just finished reading this thread because I want to know what Id be getting into with a vintage correct racer, and this by all means tells me to stay with a -4, than a -6

I watch Bring a Trailer fairly closely and when I saw the guy say that he had the reserve set at the price it cost to build the motor. Then at $30k+ and NOT selling, I knew I dont have the stomach (and wallet, more importantly) for -6 racing

https://bringatrailer.com/listing/1973-porsche-914-18/

John, you have THE "Buttercup"???

I'll stick to my subie engines 300hp/300ftlbs that need rebilt every 50k miles for $2k

Seems to easy...

Yea. That’s why I had to do at least one suby 914. $2k only gets you 20% there in a normal P6 rebuild.

My car was 1995lbs wet, last time on the POC scales. That is with full race safety equipment including a passenger seat + harness. Mag case 2.7 with extensive machine work and race mods; modded mag 914 sideshift trans. 235rwhp.

As noted, the -6 engines are frighteningly expensive to have someone build/rebuild these days. Someday I may try to do one myself. Have dreamt about a short-stroke 2.5 or a full tilt 2.8 or 3.0RSR with MFI. But even the decent cores are getting spendy.

Hey Chris,
I love 235rwhp. Pretty awesome.
When you say "extensive machine work" Are you talking about shuffle pins and boat tailing?
My case is at the machine shop now, having a hard time deciding to spend that extra change?
Shane

2mAn

What budget are you looking at, on the track and ready to race?

So I finally looked-up my engine build notes and both cases I have seem to have similar machining:

- Case savers
- Time certs
- Oil bypass mod(s)
- Full-groove/enlarge #4 main bearing
- Surface spigots
- Screw-in galley plugs
- Line bored Std/Std

The spare also has Shuffle Pins. The machine work on this spare case was ~1500 around 5 years ago. I got a great deal on the case already-done when somebody changed their build plans.

Two other important factors I remember is we used ARP studs/hardware and a 930 (IIRC) oil pump. The first 2.7 I bought already-built (which failed pretty quickly) had a 964 pump which apparently is not as robust. I think the GT3 pump is also popular for hotrod builds.

The current engine is set up for top-end power, here is a dyno sheet -

We just built a 3.0 for the track with a gt3 pump. I think the pump was around $900.

Damn...my last GT3 oil pump was $1500!

Your probably right. I’m thinking dealer cost.

My suby is a tad lighter but only 250bhp and about $1k for a rebuild or $1200 for a complete running engine.

It comes in at about 50lbs lighter than any of the Porsche 6 cylinders also.