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Old 04-11-2017, 06:01 PM   #1
CRatcliff
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Default Volvo 144 Simplest Performance Boost

Hey All!

Been reading up on things I can do to improve the power of my 144 (B20 with an F-head and K-Cam and Weber downdraft carb)

I'm wondering if y'all had a bit more specifics on what a good path would be to take for performance improvements - going from easiest with big changes, and things that compliment each other.

It seems that first steps will be Weber Sidedrafts (or Mikunis?), electronic ignition (getting mixed answers on this?), hot shot coil?

In terms of handling, things seem pretty good. I have a new front anti-sway bar (IPD), almost all new bushings (no steering play). It's definitely top heavy, so I might lower it a tiny bit, but otherwise I'm pretty happy with it.

Thank you all for your advice!
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Old 04-11-2017, 07:07 PM   #2
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A good exhaust will help release a good bit of power.

I am going to asume this is just for a fun road car. If so then a pair of twin 45's bigger valves some head porting and slightly hotter cam will do well. You can go for a decent overbore or even a stroker engine can be done

Handling wise with good bushes and all joints etc in good shape a set of 40mm lowering springs and decent dampers will have it all handling well.
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Old 04-11-2017, 07:29 PM   #3
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Awesome! And yes, just a fun road car. At this point with the downdraft carb, I'm having trouble keeping up with cars accelerating onto the highway, and I'd love to be easily accelerating faster than them. Not a race car, but something with a bit of getup. Valves are already bored out .3. I'll look into the head porting - for the cam would you suggest the IPD street?

What's a stroker engine? Sorry, new to this!
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Old 04-11-2017, 07:46 PM   #4
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Valves overbored by .3? Do you mean it has oversized B20 pistons in it? B21 pistons can be put in with a substantial overbore of the block (it's thick enough to handle it), that will increase low end torque, but it takes supporting mods to increase peak HP along with that.

A zoomier cam can be good, but it would have to be paired with supporting mods as well. The downdraft carb needs to go for sure, either stock SU's or some side drafts. The exhaust needs to be nice and free - the stock exhaust manifold/downpipe part is good, but the rest might need to be improved.

Porting, if done, is mostly needed on the exhaust ports. Larger valves, very careful bowl work and blending of the area between the new larger valve seats and the bowl (it's constricted on an F head for some reason). Intakes will generally not need much iuntil the exhaust has been improved quite a bit.

Double valve springs will also help the engine perform properly at higher revs. It's hard to meaningfully increase power at a given displacement without making torque at higher RPM's, simple math in the way HP is calculated. It's harder to increase torque without forced induction.
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Old 04-12-2017, 01:08 PM   #5
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Valves overbored by .3? Do you mean it has oversized B20 pistons in it?
Apologies - I'm not 100% sure what it all means (I'm new to engine mods of this sort), but here's the info:
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Old 04-12-2017, 01:15 PM   #6
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Thank you for the good input!

In terms of carbs:
I've been speaking with VPD and another forum member, and have a line on the dual Mikunis. They appeal greatly to me, as I have a lot of great experience with Mikuni carbs. I wanted to see if anybody had used them and could give perspective. Otherwise, I'll put the Weber sidedrafts on.

In regards to porting, what am I looking at to do that? Would I need to take the engine apart and take it to a machine shop?

When you say
Quote:
It's hard to meaningfully increase power at a given displacement without making torque at higher RPM's
, what would you suggest to make torque at the higher RPM's? From what I understand, better carbs would definitely do that.

I've also consistently heard that 123Ignition combined with a hot coil will give a pretty solid power boost. Is that correct?
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Old 04-12-2017, 01:16 PM   #7
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Looks like a factory rebuilt engine, those are just the oversizes on the pistons and bearings.

Technically speaking a .3 overbore and oversized pistons increase the displacement, in practical terms, though, it doesn't do anything noticeable.

If you're not rebuilding the engine and buying new pistons anyhow, not really worth the effort of taking out good B20 pistons and putting in B21.
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Old 04-12-2017, 01:17 PM   #8
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I've been speaking with VPD
All I will say here is do some due diligence and search around here and the rest of the internet for VPD/Vintage Performance Development/John Parker, before you send him money.
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Old 04-12-2017, 01:29 PM   #9
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All I will say here is do some due diligence and search around here and the rest of the internet for VPD/Vintage Performance Development/John Parker, before you send him money.
Oof good to know. I have a line on some mikunis that don't involve VPD, so that might be a better route if I could get reliable info on how they perform.
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Old 04-12-2017, 01:35 PM   #10
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As for the rest of my post:

Quote:
In regards to porting, what am I looking at to do that? Would I need to take the engine apart and take it to a machine shop?

When you say
Quote:
It's hard to meaningfully increase power at a given displacement without making torque at higher RPM's
, what would you suggest to make torque at the higher RPM's? From what I understand, better carbs would definitely do that.

I've also consistently heard that 123Ignition combined with a hot coil will give a pretty solid power boost. Is that correct?
Any thoughts?
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Old 04-12-2017, 02:11 PM   #11
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Mainly I'm considering getting the pertronix flamethrower and pairing it with a 123ignition. From what I can tell that should provide a pretty noticeable power boost.

Mainly I'm just having a ton of trouble keeping up with standard traffic on acceleration as I mentioned. Are my best first steps for that to do new carbs and the ignition?
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Old 04-12-2017, 02:11 PM   #12
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Making torque at higher RPM's involves making sure all the parts that flow air are all up to the task, and somewhat in synch with each other. Torque at high RPM's involves moving more air through the motor, air + gas = HP.

The carbs are the first step in that flow (well, air cleaners, but don't get too hyped up on air cleaners as something that's holding your car back). I have no experience with Mikuni's, just with SU and Weber DCOE setups (along with D-Jet, but that's a different animal). The SU carbs were very competent, and could be modified to keep up with engine mods, for a fair bit. The basic size of the carb pair was a bit overspecced for Volvo's stock HP.

As the engine mods on my PV's motor accumulated, eventually I swapped to the DCOE's. Both made plenty of low end torque, but the DCOE's kept that power going higher in the RPM range. Plus, they're more forgiving of the erratic airflow produced by a lumpy high revving cam with lots of overlap at lower RPM's. The SU's are paying careful attention to the pressure in the venturi, and positioning the mixture piston accordingly, having pressure waves coming back up out of the intakes is not helpful. The DCOE's are more 'steady state', all they do is possibly re-gas some already gassed air if it goes out and back in again.

Next link in the chain is the head itself. The valves and the ports. B18's had smaller intake valves, B20's had larger, and the injected B20's even larger. But they all kept the same exhaust valve sizes. And the exhaust ports are very awkward in terms of flow. Because the intake and exhaust is on the same side of the engine, packaging demanded that the exhaust ports be lower in the head. So they make a very sharp turn in the bowl, more than 90 degrees, and proceed out only a quarter inch or so above the bottom of the head. This is not great for flow, and while it can be improved, it can also be damaged by someone porting out the bowls that doesn't pay attention to what they are doing. But in general, bigger valves, work done on the ports on the exhaust side, and double valve springs will all get the head to flow more air at higher RPM's. Double valve springs help the valves close at higher RPM's. And OHV engine has more hardware that needs to move around as the valves open and close, the springs need to pull the valve closed, plus the rocker arm, and the push rod, and the lifter. So stiffer is better, plus the double springs also don't have a static resonance, like a single spring (can).

Next is the cam. The shape of the lobes, and research over the decades makes newer shapes that work better over wider RPM ranges. Old style cams (and you'll find lots of these for sale for the OHV Volvo motors, because they're similarly old) will have much more pronounced RPM ranges they're effective at. In addition to the lobe shape, there's the timing of the valve openings, the amount of lift (how far the valve opens), and how long the exhaust and intake valves are open at the same time. It is important to note here that a cam is (to a degree) tuned for peak efficiency at a given RPM, and this is rather pointless if the rest of the air moving parts are not effective at a similar RPM range. It all needs to work together.

Next up is the exhaust manifold. There's more to an exhaust manifold than in merely directing exhaust away from the motor and out back somewhere where it won't asphyxiate you. Simply getting the last exhaust gas pulse out of the way isn't quite good enough here, what you want to do is get the last pulse to *aid* the next one. This is all based on the diameter of the exhaust runner, how long it is, and how long it takes for a pulse to reach a merged flow with the other cylinders. This all comes down to RPM tuning again, as the rpm's rise, the length of tubing needed to have the last pulse still heading away and producing a slight pull (relative term, to the ambient pressure in the exhaust system, whatever that is) at the exhaust valve when it opens. So the next pulse gets pulled into the exhaust, instead of needing to push its way out against pressure. This is often misunderstood as 'backpressure' - because pipes that are too large can hurt power at certain RPM's, because the exhaust is merely getting out of the way for the next pulse, instead of actively helping it along some. All a bunch of words to support the notion that the exhaust manifold is tuned for a certain RPM range as well. I'm certainly not a pro at this, but what I've read form people who are (somewhat?) is that the cheap 4:1 (all 4 tubes extend for a while and all merge into one) headers commonly for sale for old Volvo's are tuned for an RPM range so high as to not be commonly used in any sort of street driving situations. What does work better are the less common, usually a bit spendier 4:2:1 headers. The #1&4 cylinders pair up somewhat quickly, as do the #2&3 cylinders. This allows those pairs of cylinders to help pull exhaust from their twinned pair, effectively getting a pulse twice as often (every 360 degrees instead of every 720) and thus working at lower RPM's. Then those two joined tubes join together into 1 pipe further down. The stock exhaust system is already configured like that, and by all accounts works very well until you've got plenty of other mods piled up.

Past that, the exhaust system just needs to stay out of the way. Once all the cylinders are merged together, you just don't want the system to have any restrictions that prevent flow at high RPM/WOT.

I think an ignition system will only produce a 'pretty solid power boost' if the system you're comparing it to is pretty weak. A properly setup 70's era Volvo ignition system should have enough pep with the right plugs to not cause you any grief. I got some improvements on mine, but that was when I replaced a very old and very weak original early 1960's style coil. Later on, I put an MSD box on it as well, which makes multiple zaps at lower RPM's which seems to help starting, low end torque, but it's not a huge difference.
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Old 04-12-2017, 02:35 PM   #13
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Awesome! OK, so, to make sure I understand:

Stock exhaust can probably be left alone for now
SU Carbs or DCOEs are going to be a huge improvement (I don't have SUs but I might be able to hunt a pair down for cheap)
Porting and cam will be a big improvement, but not as simple to do
Ignition system is probably not a worthwhile change for now

In regards to the exhaust system, to help the air flow more on motorcycles I know a frequent move (particularly when tuning carbs richer) is to leave the headers the same but switch to less restrictive mufflers / tail pipe. Is this what you meant when you said the manifolds/downpipe is good but the rest needs to change?
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Old 04-12-2017, 03:02 PM   #14
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Carbs will only be a big improvement if the rest of the engine is modded accordingly.

In other words, stock SU carbs are not holding back a stock motor. Putting DCOE's on a stock motor will make very little improvement. Above I said the DCOE's made an improvment on my car only when I had lots of supporting hard engine mods in place (2.1L displacement, R-Sport head with lots of flow, high ratio roller rockers, really zoomy cam, header, big exhaust). At *that* point, the SU carbs (reneedled to provide more fuel already) were holding the motor back some. And even then, only at higher rpms.

That Weber downdraft carb, however, is barely adequate for a stock motor.

Unfortunately, the HP of the B20 is largely restricted by the head and cam. Not that easy to fix. You'll get less of an improvement from anything else while leaving those pieces stock.

Some car companies used to put out cars with engine power noticeably gimped by one or two poorly engineered pieces. That wasn't the case for Volvo. They did hold back the power levels, but in a hard to fix manner. I think this was done on purpose so the cars would be stressed less and they'd last longer.
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Old 04-12-2017, 03:09 PM   #15
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Carbs will only be a big improvement if the rest of the engine is modded accordingly.

In other words, stock SU carbs are not holding back a stock motor. Putting DCOE's on a stock motor will make very little improvement. Above I said the DCOE's made an improvment on my car only when I had lots of supporting hard engine mods in place (2.1L displacement, R-Sport head with lots of flow, high ratio roller rockers, really zoomy cam, header, big exhaust). At *that* point, the SU carbs (reneedled to provide more fuel already) were holding the motor back some. And even then, only at higher rpms.

That Weber downdraft carb, however, is barely adequate for a stock motor.

Unfortunately, the HP of the B20 is largely restricted by the head and cam. Not that easy to fix. You'll get less of an improvement from anything else while leaving those pieces stock.

Some car companies used to put out cars with engine power noticeably gimped by one or two poorly engineered pieces. That wasn't the case for Volvo. They did hold back the power levels, but in a hard to fix manner. I think this was done on purpose so the cars would be stressed less and they'd last longer.
Makes sense. So going from downdraft to SU will be a big improvement? Or still not a big one.

Any advice on where to start looking to get head and cam work done? Would it be advisable to do all of the engine mods at once, or are there some that I can trickle in for some marked improvement? (Say, new head can be done and it isn't necessarily worth it to swap the cam at the same time?)

I don't have a cherry-picker, so engine-out stuff will probably be pretty tough.
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Old 04-12-2017, 03:22 PM   #16
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SU's and a cam would perk things up nicely. (Err... assuming you have a manual trans, getting the motor to rev more won't help much with a BW35 wet blanket).

I'd look for:
- a set of SU's or a set of DCOE's, depending on your tastes. I have DCOE 40's on my car, which are probably too small. They were, however, better than the SU's and quite cheap on eBay (lucky find). 45's would probably be better, even with the same chokes as my 40's have.
- a somewhat zoomier cam. Don't go too extreme, if the rest of the engine can't keep up, you can hurt overall power by making the cam peak power band different from the rest of the engine's peak powerband. IPD Street Perf cam (which is an olde fashioned Isky VV71) is pretty nice, I've run those in the past. Cam's can be replaced with the engine in the car, just need to remove the radiator and grille to make room for it to come on out the front of the motor.
- find a shop to do some *basic* work on the head. It has to come off to swap the cam anyhow. You probably don't have hardened exhaust valve seats, and you probably should get them installed. While that work is being done, go to bigger exhaust and have some basic work done blending the new larger valve seats up and into the bowl. F heads have a noticeable restriction between the bowl and valve seats for some reason, that needs to be gone. Don't have them do much at all to the bowl - the shape and angle of the roof there is important in getting the exhaust to make that *sharp* turn. Make it larger, and the air won't execute the turn as well. And if anything is done with the rest of the ports, just start with a polish. If anything is removed, take it off the top, *not* the bottom, taking metal off the bottom just makes the turn even sharper. Intakes probably don't need anything.

The engine can stay in the car for all of this. After working on my 16V turbo 245 engine, whipping the carbs and head off my PV's motor is refreshingly simple.
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Old 04-12-2017, 04:27 PM   #17
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You are a saint. I already own a set of 45 DCOE's, but it's sounding like having them tuned professionally will run me around $400. I have some SU's but they're missing the float bowls and need a complete rebuild.

This will be my to-do bible for the next year or so. Thank you again
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Old 04-13-2017, 01:44 AM   #18
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The absolute simplest thing you could do to boost performance is mill the head for more compression. F heads are 8.7:1 while E heads are 10.5:1. Make sure the head has hardened exhaust seats while it's off, have the valve job checked and shim or replace the valve springs with new stock parts. Remove any sharp edges from the combustion chamber left from milling and use a thin head gasket. E gaskets are .7 mm (.028") thick when compressed. The pistons are slightly below deck at TDC, so there's plenty of clearance.

You don't need dual carbs, double springs or larger valves for what you're doing. If you want that stuff, I'd be happy to sell it to you at very reasonable prices. I just don't think you need it. A 2 bbl synchronous Weber like a 38 DGAS or 40 DFI would be a better carb that will fit your current manifold and be a lot cheaper to tune than the DCOEs.
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Old 04-13-2017, 02:59 PM   #19
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The absolute simplest thing you could do to boost performance is mill the head for more compression. F heads are 8.7:1 while E heads are 10.5:1. Make sure the head has hardened exhaust seats while it's off, have the valve job checked and shim or replace the valve springs with new stock parts. Remove any sharp edges from the combustion chamber left from milling and use a thin head gasket. E gaskets are .7 mm (.028") thick when compressed. The pistons are slightly below deck at TDC, so there's plenty of clearance.

You don't need dual carbs, double springs or larger valves for what you're doing. If you want that stuff, I'd be happy to sell it to you at very reasonable prices. I just don't think you need it. A 2 bbl synchronous Weber like a 38 DGAS or 40 DFI would be a better carb that will fit your current manifold and be a lot cheaper to tune than the DCOEs.
Makes sense! Between a 38 DGAS or SUs, which would be best? I'm guessing the 32/36 that I have on there now is no good.
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Old 04-13-2017, 03:43 PM   #20
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The DGAS carb has an accelerator pump and a seperate idle circuit. It also doesn't need to be synchronized like SUs do. Besides, you already have the manifold and linkage.
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Old 04-13-2017, 04:21 PM   #21
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The DGAS carb has an accelerator pump and a seperate idle circuit. It also doesn't need to be synchronized like SUs do. Besides, you already have the manifold and linkage.
Truth. I'm honestly pretty interested in the Mikuni dual 42s, as it seems like a good carb for my current usage and plenty of room to grow. I might end up sticking with that one, and giving it a go. Agreed on the DCOEs, though, as my local carb shop was quoting $400 for tuning.
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Old 04-17-2017, 12:42 AM   #22
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I have a pair of Mikunis that came on my 122. They worked fine but had some quirks. Too tired to go into detail but let me know if you are interested. I eventually fuel injected the Amazon so the Mikunis are just sitting in my basement. Would be up for unloading them if you are interested. I also have a DGAS.

I've messed around with the old redblocks quite a bit. Of all the changes I made, porting and milling the heads had the biggest impact. Not sure how effective that would have been without all the supporting upgrades I had already made, (sidedrafts, exhaust, cam).
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Old 04-18-2017, 12:30 AM   #23
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PM sent.
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Old 04-18-2017, 01:12 AM   #24
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Quote:
Originally Posted by CRatcliff View Post
You are a saint. I already own a set of 45 DCOE's, but it's sounding like having them tuned professionally will run me around $400. I have some SU's but they're missing the float bowls and need a complete rebuild.

This will be my to-do bible for the next year or so. Thank you again
You want to have some strangers Roger you royally? $400?/ Who? My old friends downtown?

I didn't wade thru all the above but simple more power is in this order, same for any engine:

Compression.
Camshaft
Carburation...

The 3 Cs

Camshaft makes for the powercurve shape.
Powercurve shape makes the demand for the gearbox ratios

And depending on what you have or will have in the box that can be a big limter on just how much of a fun cam you can get aways with..
Make a peaky motor and the motor will go "whhaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa (crunch) duuuuuuuuuh uh uh uhhhh uuuuuuuuuuuuuuuhhh " on gearchanges and that ain't quick...

45s are fine. I have them on my little V4 and have run different motors over the year from 1886cc to 1815cc to 1730cc And won a round of US National Championship Stage rally with the damn little "spare 1730" and now with 1965cc, 38 venturis and no nothing done between those motors...

$400 is absurd..Unless you WANT to get reamed.

Some people are into that...

You need to talk to somebody with sense on Planet Earth that doesn't need to make this into "The Long March of the PLA"
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Old 04-18-2017, 06:43 AM   #25
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Weber 36/36 (DCD?) + a K camshaft gave better hp (approx 130), tuning, driveability and milage compared to the gas guzzling twin SUs. Weber 45s looks fancy but overkill for decent power boost.

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