Budget engine upgrade - what would you do?

[Nux]

I realize this is not the first thread of its kind, and I've done a lot of research - but I'm still undecided on how to spend my money best. Additionally, especially engine and ignition management options seem to be multiplying by the minute - and so does the cost.

So, what would you do this winther????

Engine now:
3.2SS from original '78 3.0 (large intake runners). Compression unknown (probably 9.3:1). Cams unknown (most likely stock). EFI converted (Bitzrace kit) with straight headers and Dansk two-in two-out. Dyno run before EFI was approx 200 wheel horses. Butt dyno tells me 210 now, which translates to 240-45 at the crank?

Is that even possible with the above specs?

Car is very light (approx 2000lb) and runs a stock 915 trans. I'm looking for more HP, but this is NOT a racecar. Will see no or very little track time. Never runs above 6500rpm. This is a hot rod and traffic light racer for fun.

And no, I'm not going for a 3.6 conversion. Thats cheating

Budget is 6000$ isch.

I don't mind doing the work my self - and I have access to very competent help for maching heads or fitting throttle bodies etc.


Option A:
ITB and ignition/fuel management. Will I gain anything substantial other than driveability, even better throttle response and very very cool looking engine bay? 10HP?

Option B:
Change compression to 10.1:1 (using existing cylinders if possible) and ad a 964 cam? Gains 15-20HP?

Option C:
Raise compression to 11.1:1 and dual plug. Leave cams for now, with an option to upgrade later on. 10% HP gain? Possible within budget????

Option D:
Port and polish heads and ad 964 cams. Does this even work on an old 911? (used to port and polish my race bikes - THAT worked).

Option E:
You tell me!!!!

Thanks, Martin

[Catorce]

Porting the heads and adding more aggressive cams seems like its within the realm of possibility - will definitely add more power.

[trond]

I'd go for ITBs for improved throttle response. You already have the bitz kit and can use it, except you'd have to re-program from pure MAP to TPS...

[fred cook]

Depending on your budget, I like the option C idea. Especially if you change over to a direct fire ignition system such as the Electromotive XDi. Doing this would mean either machining the heads or replacing the pistons or both. The heads will have to go to the shop to be cut for the second spark plug anyway and I would have a top end job done while they were at the shop. If you did all this, you would probably spend around $4K or so. Good luck!

[Tippy]

ITB's and cams would be my vote. Both can bring big hp increases. Together would be a different engine guaranteed properly tuned.

[trond]

If involving twin spark the only way to not completely blow the budget would be to go
EDIS. May even use the distributor.... Cheap and good and OP has MS already so easy too

[Nux]

Thanks for the reply guys. I think I have decided on the ITB + Ignition.

Trond: I see you have successfully used EDIS with Megajolt. Is that easy to install and tune? And goes well with the Tbitz EFI? If so I would be tempted to go for Al Kosmals ITB setup with TPS modification to existing MS together with EDIS and Megajolt.

OR maybe even modify the ITB for MAP and leave the MS as is??????

Check this out: https://wiki.autosportlabs.com/MJLJ_V3_vehicle_installation_guide#Load_Sensing:_M anifold_Pressure_Sensor_.28MAP.29_or_Throttle_Posi tion_Sensor_.28TPS.29

anyone done this on a 911?

[Nux]

ahhh found it...

How to get good vacuum with ITBs?

Drill or Dont Drill (ITBs)

So it can be done!

[trond]

Megajolt is easy to install and tune and you can run it in parallel with MS. Having done that, and later converted to MSII with spark, I recommend expanding the MS. As easy and fewer boxes. Even I did the swap and programming of the new CPU in hours. Better tuneability with idle settings, cold start settings and so on. I am now running MS2 with spark and using Tunerstudio it is a wonder in userfriendliness. Thats what I recommend

[m42racer]

Originally Posted by Nux

I realize this is not the first thread of its kind, and I've done a lot of research - but I'm still undecided on how to spend my money best. Additionally, especially engine and ignition management options seem to be multiplying by the minute - and so does the cost.

So, what would you do this winther????

Engine now:
3.2SS from original '78 3.0 (large intake runners). Compression unknown (probably 9.3:1). Cams unknown (most likely stock). EFI converted (Bitzrace kit) with straight headers and Dansk two-in two-out. Dyno run before EFI was approx 200 wheel horses. Butt dyno tells me 210 now, which translates to 240-45 at the crank?

Is that even possible with the above specs?

Car is very light (approx 2000lb) and runs a stock 915 trans. I'm looking for more HP, but this is NOT a racecar. Will see no or very little track time. Never runs above 6500rpm. This is a hot rod and traffic light racer for fun.

And no, I'm not going for a 3.6 conversion. Thats cheating

Budget is 6000$ isch.

I don't mind doing the work my self - and I have access to very competent help for maching heads or fitting throttle bodies etc.


Option A:
ITB and ignition/fuel management. Will I gain anything substantial other than driveability, even better throttle response and very very cool looking engine bay? 10HP?

Option B:
Change compression to 10.1:1 (using existing cylinders if possible) and ad a 964 cam? Gains 15-20HP?

Option C:
Raise compression to 11.1:1 and dual plug. Leave cams for now, with an option to upgrade later on. 10% HP gain? Possible within budget????

Option D:
Port and polish heads and ad 964 cams. Does this even work on an old 911? (used to port and polish my race bikes - THAT worked).

Option E:
You tell me!!!!

Thanks, Martin

The first question you need to answer to yourself is, what performance upgrade are you expecting? You have a budget, so now decide if the budget is aligned with your performance goal.

$ 6000.00 will not achieve much so its important to decide upon something that is realistic and wont drag you past the $ 6K budget.

ITB's will cost approx 4K right there. that leave you 2K for all of the other stuff. Not possible in my opinion.

If the engine has CDI ignition already, if its working OK, leave that alone. Do not go to any sort of Inductive type as the ignition performance will suffer. Twin plug makes the inductive attractive by cost only. The twin plug system will allow you to advance the timing point some, but if the ignition power is less, what have you gained.

You can gain 10+ HP by making the engine as it is more efficient. Get the engine to pump the air better, so any restrictions in the intake system can be looked at. Have your friend flow the heads and the intake if he has a bench and see what it flows. Then measure the cam you have now. See what the LSA number is. Something around 104- 106 is a good place to start. Maybe you can add some duration which will increase the area under the curve some, if the heads will allow. Measure the CR so you know where you are at. Maybe you could bump that some, but you first have to know what it is.

Too many get caught up in hot rod'ing with brand new parts without even knowing what they have to start with. Establish what you have and see if you can make that better without bringing new parts into the equation. Once you know where your weaknesses are, you can better choose the parts and upgrades that will make the most difference with the budget you have.

Your hip just connects the leg to the rest of your body. That's its job. It was never designed to measure and decide upon engine upgrades. Shooting from the hip was OK back when decisions were made with a Colt. Not today.

[Nux]

Yes you're right. However, Al's solution for ITB is much cheaper at 1900$ for a complete kit, while Jenveys are listed at 2500$. EDIS and coilpack is max 500? So if I'm not completely off the whole deal should be less than 3000?

Al even has a complete deal including Rasant AEM for 4200$. So hopefully I'll be able to keep cost below 6k nomatter what.

[m42racer]

Good luck and I hope you end up, with what you are expecting.

In my opinion you are going about this all wrong. An engine upgrade has to be based on the performance expected and not the cost. The cost surely makes you compromise the upgrade but if that cost is the driving factor without knowing the outcome, you are heading in the wrong direction.

ITB's will or could make the Throttle response better but only as much as the current engine will support. Your choice of Ignition is completely wrong for a combustion chamber the size and shape you have.

Assuming you go this route, the ITB's are chosen to make the engine response better but the Ignition will work in the opposite direction.

To help you understand what I am saying, when you have your new Ignition system fitted, fit some wet and fouled plugs. Try to start the engine. It probably will not start until you fit clean plugs. Inductive systems do not have enough horsepower to overcome fouled plugs.

A CDI system will fire and start an engine with fouled plugs. My point is not about fouled plugs but about Ignition energy levels. Starting an engine with fouled plugs takes a lot of energy as does generating the temperature inside a chamber with higher than atmospheric pressure. This is what you feel when you step on the throttle pedal.

[trond]

reasoning behind my voting for ITBs are;

Option A - ITB would/should/could give better part throttle response. Great for town&street driving ! Always loved flatslide carbs on bikes

B - you already have 98 mm aftermarket pistons. Very possibly these are higher compression than 9.3 ? If so little gains would to be had from changing pistons for just a few points.. Also I would guess you might not like that much the loss of low down torque with a cam swap. I know I did'nt. Depends on use&taste

C-11.1:1 sounds excessive. I am doing a conversion to 10.5:1 & twin spark right now, and can confirm it is doable within your budget. I am using pistons&cylinders from EBS, I already have EDIS crankfire ignition and easy and cheap to expand the system for twin spark. Personally I would NOT do this if I had a well working engine but I had to do something with the oil smoke issue

D - Port and polish&cam. You already have large port heads. How much better can it get ? And if you like the driveability now with stock cams you might not enjoy a hotter cam. I know I hated mine and I am much happier now with stock cams. I believe I am quicker too in real world driving too.


So I am still with ITBs using tbitz EFI. Don't touch the engine itself if it is working well. Upgrade to MSII and crankfire EDIS and get someone in the know to map the ignition. Should be awesome, and possibly within budget. Anyways well worth it

[Nux]

Originally Posted by m42racer

Good luck and I hope you end up, with what you are expecting.

In my opinion you are going about this all wrong. An engine upgrade has to be based on the performance expected and not the cost. The cost surely makes you compromise the upgrade but if that cost is the driving factor without knowing the outcome, you are heading in the wrong direction.

ITB's will or could make the Throttle response better but only as much as the current engine will support. Your choice of Ignition is completely wrong for a combustion chamber the size and shape you have.

Assuming you go this route, the ITB's are chosen to make the engine response better but the Ignition will work in the opposite direction.

To help you understand what I am saying, when you have your new Ignition system fitted, fit some wet and fouled plugs. Try to start the engine. It probably will not start until you fit clean plugs. Inductive systems do not have enough horsepower to overcome fouled plugs.

A CDI system will fire and start an engine with fouled plugs. My point is not about fouled plugs but about Ignition energy levels. Starting an engine with fouled plugs takes a lot of energy as does generating the temperature inside a chamber with higher than atmospheric pressure. This is what you feel when you step on the throttle pedal.

well, just a quick update: I decided to stay with a CDI system and recently upgraded to the CDI+ from Classic Retrofit. Very nice product which gives me CDI power combined with full ignition control and "dual spark" (if one believes in that....).

Next will be Al's ITB solution and more agressive cams.

[smokintr6]

I would NOT spend money on ITBs, I've had them, and im not impressed for a street car. When you go ITB, to take advantage of them you should have a more aggressive cam, and you're looking to maximize HP, and not necessarily a good street torque curve....

I would bump the compression to match 964, go twin plug, make sure the heads are still in good shape and maybe clean up the castings, and pick out a cam that works with a manifold. I would also want to experiment with some of the variable volume intake plenums (964 or 993). For a street car, area under the curve is where it's at, peak horsepower is not really what you should be concerned about.

That being said there is really no argument that you can make against selling your current engine for at least $7k if it's healthy, and put the other $6k into a 964 engine. My car is 2600 lbs now, and has a stock 964 engine. It's 10000 times more fun to drive than my old engine which was a 3.6 with ITBs, RSR cams / heads and was a MONSTER from 4K to 7500 RPM. It did 300 RWHP on a dyno, and it was still less fun than the stock 964 engine. Especially around town. From 1 to 4k rpm its was somewhere between a stock 911 SC and a stock 3.2 carrera, feel wise. The stock 3.6 torque rips around town!

[Nux]

Hmmmm that is very interesting!

My car is 2000lbs now - so very light weight. Still a matching nr's car and I would like to keep it that way. So the 3.6 swap is No-go.

But I would love a twin plug high comp sleeper. Will look into the 993 plenum as suggested.

[m42racer]

Originally Posted by Nux

well, just a quick update: I decided to stay with a CDI system and recently upgraded to the CDI+ from Classic Retrofit. Very nice product which gives me CDI power combined with full ignition control and "dual spark" (if one believes in that....).

Next will be Al's ITB solution and more agressive cams.

Now your'e talking. The choice of CDI over Inductive is the right one. Now choose everything else with the same care.

Well done.

[lvporschepilot]

You will get much more than 10bhp from ITBs, 20bhp is much more likely. There is good documentation around somewhere showing a stock good running CIS 2.7 making 23bhp just swapping to ITB. That stock throttle body is hugely limiting. Change to ITBs and swap the cam for something a bit hotter that can work with your compression and you're done