PRODUCT DETAILS
SpeedFactory Ram Horn Turbo Manifold - Honda B-Series & D-Series
If you're building a serious turbo B or D and you want a manifold that lights a big turbo up early and pulls all the way to the top, this is the one. SpeedFactory's Ram Horn runs an equal-length design that spools even the largest turbos fast, and it's fabbed to a standard that holds up to what a real drag car does to a manifold. But before you get excited about the spool numbers, there's one decision you have to make first, and it's not about the turbo.
Read This First: The A/C Has To Go
No way around it, so let's be upfront. This manifold requires removing your air conditioning system. There isn't a workaround, the Ram Horn's runners live where your A/C components live, and something has to give.
So be honest about your car. If it's a dedicated drag or track car, this is a non-issue, the A/C came out years ago and you're just here for spool. But if the car still sees summer traffic and you've got any attachment to cold air, don't order this one. SpeedFactory makes an A/C-compatible Ram Horn specifically for street cars, and it's the smarter buy for that build. Fair warning though, the A/C-compatible version is built around small to medium T3 turbos only and comes with a 38/40mm V-band gate for clearance reasons. So if you're hanging something big off the head, this is your manifold and the A/C is your trade.
Why The Ram Horn Spools Like It Does
Here's what the design buys you. Equal-length runners mean the exhaust pulses from each cylinder arrive at the turbine evenly spaced and with their energy intact, instead of colliding with each other on the way in. Clean, evenly-timed pulses are what actually drives a turbine wheel, so the turbo comes alive earlier and keeps making power up top instead of falling on its face. That's the combination this thing exists for: big torque and quick spool down low, plus real top-end horsepower when you're wringing it out. It'll wake up turbos most manifolds struggle with, which is exactly what a drag car wants.
The Flanges Are Where Leaks Get Killed
Anybody can bend tube. The flanges are where a manifold earns its money, because that's where boost and exhaust go looking for a way out. SpeedFactory CNC machines the cylinder head, wastegate, and turbine inlet flanges from 1/2" 1018 steel plate, and here's the part that matters: every mating surface gets machined dead flat. Thick, flat flanges don't warp their way into a leak after a few heat cycles the way thin ones do. Add the 1.5" schedule 40 stainless tube, TIG welded and back purged (they flood the inside with argon while welding, so the weld root comes out clean instead of sugared and brittle), and you've got a manifold that seals when you bolt it up and keeps sealing.
Pick Your Engine and Wastegate
Two things to sort before you order. First, choose your engine, it's offered for both B-series and D-series. Then match the turbine flange and wastegate flange to the parts you're actually running:
- T3, 38-40mm 2-bolt
- T3, 38-40mm V-band
- T3, 44/46mm V-band
- T4 Open, 38-40mm 2-bolt
- T4 Open, single 44/46mm
Match the turbine flange to your turbo (T3 or T4 Open) and the gate flange to the wastegate sitting on your bench. Going big? T4 Open with a 44/46mm gate gives you the boost control a serious build needs.
What You Get
- SpeedFactory Ram Horn turbo manifold for B-series or D-series
- Equal-length design for fast spool and a broad powerband
- 1.5" schedule 40 stainless steel, TIG welded and back purged
- Cylinder head, wastegate, and turbine inlet flanges CNC machined from 1/2" 1018 steel plate
- All mating surfaces machined flat for a leak-free seal
- Five turbine flange and wastegate configurations
- Requires removal of the air conditioning system
Fits These Setups
- Honda B-series engines
- Honda D-series engines
Note: Requires removing the vehicle's air conditioning system. If you need to keep A/C, SpeedFactory's A/C-compatible Ram Horn is the alternative, though it fits small to medium T3 turbos only. Select your engine family and wastegate flange before ordering. One manifold per order.