Getting more power from an injected motor

WhiteyM

WhiteyM

True Classic
I've got the bug again and I'm thinking about buying a later model X (circa '85-'86) with fuel injection. What mods I can make for more power? In the early 1980s I modified a 1290 with a 1600 PBS stroker, dual Webers, etc. but I'm unfamiliar with the later 1500 FI engines and have a few questions.

What's the stock CR on these? Do the 1500 heads use the larger (40mm) intake valves? Does porting help a lot? Can the CR be raised by merely milling the head, or would I need to install different pistons?

How much would the FI unit limit HP if I were to install, say, a moderate performance cam, do some porting /head work, header, free flow exhaust, etc?

Is the stock bottom end fairly rugged and reliable? I used Cosworth 10.5:1 pistons and Crower rods on my previous X but I'm hoping stuff like that wouldn't be necessary on a mildly warmed-over 1500.

If I buy a later model I'd be looking for a very clean, low mile example and just make a few basic mods to turn it into a nice street car. What would be the recommended mods for such a project? Am I correct in assuming a ported head (maybe milled) with something like a 35/75 or 40/80 cam, plus a good exhaust would wake it up? Any good reading on this subject?

Many Thanks!
 
Ramblings

We're in opposite sides of the same boat. I've had my '76 since '78 and have long planned to build a hot 1600 for it-- even have collected quite a few of the needed parts over the years. In the meantime I recently acquired an '85, which I am in the process of mildly modifying until I have time to build the 1600, for which the '85 will serve as a test bed.

So I've thought quite a bit about the best way to get a little more power out of the 1500 FI motors. By far the best resource I've found is the archives on the original Xweb-- you'll find tons of useful info if you're willing to spend the hours.

As to your questions, there aren't all that many differences between the 1300 and the 1500 motors. Compression is 8.5:1. The block is taller, the pistons and crank are quite similar except for dimensions, the later rods are much better (sleeker profile and forged rather than cast). You virtually never hear of anyone breaking anything in the bottom end of an X motor unless there's something else wrong. Which tells you there's no need to change rods or pistons in a street motor unless you just want the lighter reciprocating weight.

The 1500 is quite lazy at higher RPM, which indicates that it's breathing limited. The later heads breathe best of all the X cylinder heads but there's plenty of room for improvement. Stock exhaust valve size went up In the 1500 but the intake valves remained the same as in the 1300 motors.

From looking at both the stock FI head and a Euro head I think the biggest gains are actually in the combustion chamber, unless you were to install larger intake valves (which is a very good idea if you're willing to spend the bucks). Chamber work and mild port work will greatly improve the flow and power potential of the stock head (see my post on the old forum for details). The downside is it lowers compression even further because of the material removed from the chambers.

Many here have bumped their compression ratios by milling away the recess milled into the combustion chambers of US cylinder heads. That should get you about half a point of compression since Euro motors had a 9.2:1 ratio and as far as I know the only differences were smaller valve reliefs in the Euro pistons and the lack of the ~.065" chamber relief.

The downside there is that you take strength out of the head and you're not fully optimizing flame travel. The ideal solution appears to be to use a Euro head and deck the block to raise compression even further. But you could likely get very nearly the same effect by cutting both the head and the block if using US spec parts. You would need an adjustable cam sprocket to compensate for the retardation of the cam timing.

CW here is that a 35:75 cam is the max you can run with the stock injection but I can't confirm that through firsthand experience. I've gotten pretty radical cams to work okay with stock injection systems in other cars but it wasn't easy.

The stock injection is an impediment in a couple of ways. First, it was never designed to support anything more than the anemic stock powerplant. Second, the airflow meter is a huge restriction in the intake air stream, which really kills torque. You could pick up a fair amount of power simply by going to an injection system that does not use an AFM. But that's not to say that you have to...

For your stated purposes you could rebuild the stock bottom end, decking the block and carefully balancing the rotating assembly in the process. Do some mild port work and some moderate chamber work, add a Euro cam or the aftermarket equivalent. Mill the head in conjunction with the block to try to get compression up and optimize flame travel. Use an adjustable sprocket to dial your cam timing in, add a long tube header and the lightest flywheel you're willing to shell out for, and you'd wind up with a more poweful, driveable engine without spending a fortune or losing reliability. If you're willing to spend more $ a big valve head with bigger ports (and matching intake), along with a different injection system, would help a bunch.

Now, I'm hoping others will weigh in with ideas I might have missed so I can include those in my own build. :)

HTH,

///Mike
 
I'm with ///Mike...

The fuel injected motor that he proposes is very close to what I built in my '81 X, with the exception of the exhaust. I was in California, USA which has quite stringent smog regulations. I left the stock exhaust manifold, downpipe and catalytic converter in place, building 2 inch turbo muffler system downstream.

The car ended up at about 9.4:1 compression, had a PBS SX-1 cam and was very tractable and powerful. I never touched the bottom end other than putting in a higher pressure relief spring in the oil pump. Plus, it passed the stringent smog testing.

If you can upgrade the exhaust system, only go with a long tube header - IAP style, or with a dual outlet exhaust manifold and system ala '74 North America X1/9 or Euopean X. The shorter tube PBS style header is not ideal for street use.

Ciao,
 
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Thanks for the quick replies Mike and Mark. Since I first posted, I visited the Bayless site out of curiosity and see they don't recommend using a cam with any of the FI cars; they say they've tried but just didn't get good results. That's really a bummer. If I were to find a real clean, unmolested later model car I don't think I'd want to be making TOO many visual changes under the hood by swapping out the FI system with something aftermarket. And since the stock FI system is a limiting factor, then, I guess I'd have to be content with minimal modifications. I'd still look at bumping the compression, a mild cam, and exhaust. Yes, I live in CA with our draconian smog laws but that's the least of this state's problems right now and like many others we might be relocating soon, maybe back to the midwest.

So the FI X's use an AFM? My '85 BMW 635 does too, and many guys with older Bimmers are swapping out their AFM unit (which often goes bad) with an MAF which is (in theory, at least) much less restrictive. However, I've also heard that if the AFM is still operating properly, you won't notice much difference in HP with the MAF but throttle response will be better.

I'm surprised PBS is still in business! Are they still a good source for parts? Any idea of the specs of the SX-1 cam you mentioned, Mark?

And Mike, when you mentioned the "later" rods were forged rather than cast, I assume you mean all 1500 rods, correct?

God, I'd love to hear what Al C. would have to say about this topic...but he probably wouldn't even bother with an injected car. I bought many parts from him (along with PBS) in the late '70s/early 80s. Are there any other sources of high-perf parts for X1/9's today besides Bayless? They don't seem to have much for the X in their online catalog. Neither does IAP. And where could I find a Euro head?

It's kind of frustrating working with X1/9's; the original '74 model with its small bumpers was the best looking, the carb'd cars were the easiest to modify, and the injected cars were the most refined but also the most difficult to extract performance from. I guess you can't have it all in one package.

I feel like I have so many questions. Great info, guys!
 
For high-perf parts call

Matt at Midwest X1/9 he is Bayless .As fair as Al he is still vary sick and can not comment even if he wanted to .As for a 35/75 cam in a FI car you can do it again cheek with Midwest X1/9.Matt just bout Bayless and is still moving all the parts so it won,t be easy to reach him right now but when you do he is the coolest guy and will help you.
http://www.midwest-x19.com/
 
racerx,

Thanks for the referral to Midwest X1/9. I'll have to see what he says about the cam usage. I see you're in St. Charles; I lived in Aurora from 1978-1987. Are you the guy who said he spotted my old X1/9 at the community college in Sugar Grove in the mid-80s?

That X for sale is the right color (red) but quite frankly it's pretty rough, rust-free or not. I'm not looking for a restoration project ($$$ and time) although I don't mind some engine work. I'm sort of sitting on the fence about taking a plunge into another car until the economy stabilizes a bit, however if the right one came along...

Larry
 
Yes...

All 1500 rods are forged.

A couple of responses to your reply:

As has been noted, you probably don't want to run a wild cam with the stock EFI but you can easily improve the breathing with a mild street cam. I am planning to run a Euro cam because I have one, but I would likely go for something like a 35:75 cam if I needed to buy one. You might be better off with a slightly milder cam (not that a 35:75 is very wild) since you're in The People's RepubliK of CA.

See Mark's post for an excellent example of what can be done pretty easily and still remain smog legal. The only thing I would add would be to go ahead and balance the entire rotating assembly.

I think removing the AFM would be a big improvement. It interrupts the momentum of the intake air charge, reducing the amount of air that actually enters the combustion chamber. Removing that restriction would result in a significant improvement in the phenomenon known as "inertial supercharging", where the weight of the fast moving column of air in the intake tract actually forces a greater volume of air into the combustion chamber than the chamber actually displaces. This increases torque (also horsepower) and is responsible for the improved "throttle response" (torque) mentioned by the 6er owners. I'm a big fan of MAFs, and plan to use one myself. Allows the use of wild cams too. :)

I would disagree with the assessment that the later cars are the most difficult to extract more power from, although it is true that the additional weight means you need even more power to feel the same results as you would in a lighter car. The 1500 is a better motor in every respect than the 1300, although it doesn't rev nearly as happily in stock form. But it's still a vastly oversquare motor, so it's not like it *can't* rev very happily. It's just that the breathing didn't keep up with the displacement increase so you wind up with torque down low and wheezing above ~5k. The nice thing is, that's easy to fix as detailed above.

I would submit that a 1500 with stock injection could make more power than a 1300 with any single carb setup, assuming we're talking about the same fuel and emission requirements. Sure, a dual carb 1300 would be quicker in a lighter car, but it ain't gonna pass visual or tail pipe testing.

You could do pretty much as Mark did (Mark is a great resource and very knowledgeable about these cars) and wind up with as much power as you can get out of an emissions legal car. If you later move somewhere with less onerous restrictions you could swap cams and or get rid of the AFM for even more gains without losing reliability or driveability. And you could also gain real world performance by lightening the car, which would improve all aspects of performance, and even gas mileage. :)

HTH,

///Mike
 
Hey Mark...

You're running a measured 9.4:1 on 91 octane?

Trying to learn how much compression one can actually get away with....

///Mike
 
A few points to consider.

An issue with the stock fuel injection system is that it is programed for emissions and is a MAP based program. Changing the camshaft causes pulses in the manifold pressure that cannot be compinsated by the Bosch system. My 79 car is running on MegaSquirt and is using a Throttle Posistion Sensor for Fuel management. With a 40-80 camshaft the MAP value swings by 20 MPA at idle, so a smooth idle cannot be obtained. The Bosch system uses an on off switch on the TPS and cannot be used with MegaSquirt. A variable TPS sensor must be installed. John Allen was working on a plug and play system for the X that would be more suitable for increased compression and camshaft changes.

Take a look at these links for some of the Mods that I have done to my car to increase compression, exhaust modification and fuel injection. The car now runs very well and wants to rev up. For 29 years I ran a 36DCNF on the car, problem is that run on was a big issue when hot. Fuel injection has totally stopped that problem.

http://xwebforums.com/forum/index.php?threads/4010&highlight=TonyK

http://xwebforums.com/forum/index.php?threads/2858&highlight=TonyK

http://xwebforums.com/forum/index.php?threads/1758&highlight=TonyK

http://xwebforums.com/forum/index.php?threads/1757&highlight=TonyK

http://xwebforums.com/forum/index.php?threads/497&highlight=TonyK

TonyK.

Grimsby Ontario Canada.
 
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Yes thats me

well if it a clean car your looking for theres one in Sugar Grove ,IL
hear is the add that is posed on CHI-FLU site
Tim North met up with someone at the Plainfield Cruise Night selling a 1986 X1/9. We checked out the car tonight and overall the car is in pretty good condition. The car came from Arizona about 3 years ago, but it does have a few issues mostly cosmetic. Although we started the car we did not take the car for a ride. The worst issue is some rust starting under the paint around the windshield. This would need to be addressed immediately. Other issues are: Missing Tron hubcaps (these are pretty much unobtanium), the regular amount of paint chips for a car this age, some slight oil leaks better than most, heater lever frozen, a few lights out, a broken interior door handle. Owner is Mike Marcucci (630) 334-9268 Sugar Grove, IL Looking for $4200 might be negotiable. You can view some pictures here.
http://s255.photobuck..
 
I would say that 9.2 - 9.4 compression is about it.....

with the 91 octane. I obtained the 9.3:1 compression (just checked my calculation sheet) by milling the head three different times on rebuilds. At the end, there was about a .005 inch step left and the chamber volume was about 32cc. The car had Abarth valves which are shaped for better flow. I used a stock head gasket (thinner than a Fel-Pro) and I think that I was lucky in that the deck height had the pistons just .005 inch recessed in the bores. The deck heights are a bit of a crap shoot, I think, as they are highly dependant on build tolerances, etc.

Other things that I did on the engine were to smooth all the ports, match ports, smoothed the interior of the exhaust manifold, bell mouthed the intake throttle body. I always kept the car in top tune, with all of the valve adjustments spot on.

It did run better on premium fuel, and I did not feel like playing around with how lean / poor fuel that I could go. It did not ping even though I ran it at 11*-12* static advance.

I suspect that you could run a bit higher compression. Especially if you backed off a bit in spark advance. The SOHC head design is a very octane tolerant design, unlike the DOHC head. If you look in your shop manual at the cross section of the engine, the combustion chamber shape and spark plug position are ideal for propagating an even & consistent flame front. That is why pop-up pistons are not a very good idea in these engines - the pop-up interferes with the flame travel.

I based a lot of what I did on that car on research done by Charlie Rockwell in the Bay Area. He was a tuner and Weber expert who ran his own dyno. He did a modified but smog legal FI X1/9 for himself and chronicled it in the Fiat America Club newsletter, the F.A.S.T. Archives of that may be available.

Oh, and the specs for PBS Engineering cams are at: http://www.pbseng.com/Camdata.html
Ciao,
 
I'm going to second Mark on not using pop-up pistons on this engine.
Years ago, Bob Boig who did a "cost less limited" race effort in SCCA had Wiesco make up some higher than stock compression height pistons to increase compression without decking the block. It's quite similar to Matt's current offering.

If Bob discovered pop-up pistons worked better, it would have been done.

The current engine in my X has the block decked 0.04", head 0.05" and a fel-pro head gasket with small valve pocket pistons. The resulting compression is near 10:1. It does run OK on 92 octane with the ingition advance limited to not more than 10 degrees static.

Other engine details, cam is an Abarth 21280 cam, PBS big valve head and stock_ish Bosch EFI, PBS headers with cat and Dynomax muffler. All rotating assemblies are finely balanced with ARP hardware con rods, main caps, head studs and flywheel bolts with 10mm dowel pins.

The engine runs well and easy to 8,000 rpm, but I would be surprised if it produced much more than 100 RWHP.


Mark Plaia said:
I suspect that you could run a bit higher compression. Especially if you backed off a bit in spark advance. The SOHC head design is a very octane tolerant design, unlike the DOHC head. If you look in your shop manual at the cross section of the engine, the combustion chamber shape and spark plug position are ideal for propagating an even & consistent flame front. That is why pop-up pistons are not a very good idea in these engines - the pop-up interferes with the flame travel.

Ciao,
Click to expand...
 
Yep

I agree with you and Mark-- popup pistons are a bad idea for these combustion chambers. In fact, according to an engineer I know he'd rather use flat top pistons in pretty much any motor. That's why I made references to paying attention to flame propagation in my original post. Besides, as you and Mark have pointed out, one can get plenty of compression without changing pistons.

Bernice, your engine sounds very much like what I'm planning for my interim powerplant, except for the BVH (saving that for the 1600). What are the specs on the 21280 cam? What's not stock about your stock-ish L-Jet? I've been thinking adjustable FPR. Comments?

100 RWHP ain't bad out of a 1500 with L-Jet. That'd be a substantial improvement over my current box-stock motor, even if the car would still get beaten off the line by soccer moms in Dodge Caravans. ;-)

Thanks,

///Mike
 
Hey Whitey... welcome aboard!

I see ya live out in sunny Camarillo... and just gotta let ya know... that '76 and later X1/9s still need to pass VISUAL and TAILPIPE testing here.

Soooo... ya can do a lot of what these fine folks tell ya, but every two years you'll need to dress down the motor and run methonal or alcohol, especially with a 35/75 cam. Don't forget the CAT too, and a K&N filter can cause it to fail also.

Hate to be the bearer of lousy news, but maybe ya know all this stuff as well.

I'm out in Santa Clarita... if yur ever out this way, give me a shout.
 
Hello Mike,

The Abarth 21280 cam looks like this:

At zero clearance:
Lift (intake and Exhaust are the same): 9.98 mm (0.393 in.)
Duration: 340 degrees
Overlap: 111 degrees
Lobe Separation: 103 degrees
Normal Running Clearance (0.011 in.)

These cams are very rare. They were sold by Abarth in the 70's as a performance aftermarket part for the SOHC engine back in the day. I have no idea how many were imported.

If you're going to deck and shave block and head to gain compression, the block/head gasket/ cylinder head alignment sleeves (two) will need to be shortened (to about 0.350" height) and the timing belt tensioner bearing will need to be enlarged (somewhere about 2.4" dia) depending on how much the block deck and head is lowered from stock. Actual dimensions required will vary.

The AFM flap spring tension was lowered to help the Abarth cam run a bit better. Other than this and tweaking the mixture screw, upgraded hoses, cleaned/flow matched injectors, it's completely stock. The Bosch EFI is the power output limiter on this engine.

Regardless, the engine is VERY responsive, FUN and not that slow (maybe 9-8_ish seconds 0 to 60 Mph). On a twisty back road, it's simply a joy due to it's throttle response and willingness to rev. This X will run to 120_ish Mph...my lips are sealed beyond this.....

As Papa Tony pointed out, the K & N filter alone does make a difference, even on a totally stock engine.

Bernice

///Mike said:
I agree with you and Mark-- popup pistons are a bad idea for these combustion chambers. In fact, according to an engineer I know he'd rather use flat top pistons in pretty much any motor. That's why I made references to paying attention to flame propagation in my original post. Besides, as you and Mark have pointed out, one can get plenty of compression without changing pistons.

Bernice, your engine sounds very much like what I'm planning for my interim powerplant, except for the BVH (saving that for the 1600). What are the specs on the 21280 cam? What's not stock about your stock-ish L-Jet? I've been thinking adjustable FPR. Comments?

100 RWHP ain't bad out of a 1500 with L-Jet. That'd be a substantial improvement over my current box-stock motor, even if the car would still get beaten off the line by soccer moms in Dodge Caravans. ;-)

Thanks,

///Mike
Click to expand...
 
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Hi Tony,

Yes, I'm all too aware of the over-reaching smog laws here..."one more reason to escape from California" as the saying goes. We USED to have a rolling exemption but now it's fixed at anything '76 or newer. I wouldn't be surprised if someday they start coming after us with the crusher; all those kids graduating with degrees in environmental science are itching to go work for government and figure out new ways to get more of our cars off the road. Anyway, as I stated: we might be joining a lot of our friends and be getting outta here before too long.

Is a 35/75 cam really all that radical? I thought it was relatively safe for smog. What's the overlap and true duration * .050" lift? (I ran a 45/85 cam in my old X1/9; now THAT was pretty radical!)
 
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